feat(stepfunctions): add support for EncryptionConfiguration (#30959)

### Reason for this change

Allow customers to specify a customer managed KMS key and data key reuse period to encrypt state machine definition and execution history and activity inputs. The underlying `AWS::StepFunctions::StateMachine` and `AWS::StepFunctions::Activity` resources currently expose this through an optional `EncryptionConfiguration` property.

### Description of changes

Activity and StateMachine accept a new field called encryptionConfiguration of type `EncryptionConfiguration` in their respective props. We have two separate classes which inherit the base class: 1. `CustomerManagedEncryptionConfiguration` 2. `AwsOwnedEncryptionConfiguration`

`CustomerManagedEncryptionConfiguration`:

`kmsKey`
 - Type: `IKey`
 - Description: Symmetric customer managed KMS key for server-side encryption of the state machine definition and execution history (when provided in StateMachine Props), and Activity Inputs (when provided in Activity Props)
 - Default: `undefined`

`kmsDataKeyReusePeriodSeconds`:
 - Type: `Duration`
 - Description: Maximum duration that Step Functions will reuse customer managed data keys. When the period expires, Step Functions will call `GenerateDataKey`. Must be a value between 60 and 900 seconds.
 - Default: 300 sec


`AwsOwnedEncryptionConfiguration`
- Doesn't accept any fields


### Permission Changes

#### Activity:
 - When the customer provides `kmsKey?` the key policy will be updated with the following policy statement:
  ```
{
            "Effect": "Allow",
            "Principal": {
                "Service": "states.amazonaws.com"
            },
            "Action": [
                "kms:Decrypt",
                "kms:GenerateDataKey"
            ],
            "Resource": "*",
            "Condition": {
                "StringEquals": {
                    "kms:EncryptionContext:aws:states:activityArn": "arn:aws:states:<region><account_id>:activity:<activity_name>"
                }
            }
}
  ```

#### StateMachine:
 - When the customer provides `kmsKey?` the key policy will be updated with the following policy statement:
  ```
{
            "Effect": "Allow",
            "Principal": {
                "Service": "states.amazonaws.com"
            },
            "Action": [
                "kms:Decrypt",
                "kms:GenerateDataKey"
            ],
            "Resource": "*",
            "Condition": {
                "StringEquals": {
                    "kms:EncryptionContext:aws:states:stateMachineArn": "arn:aws:states:<region><account_id>:stateMachine:<statemachine_name>"
                }
            }
}
```

- If the state machine contains an activity which uses KMS encryption, the state machine execution role will be updated with the following permissions
```
{
            "Effect": "Allow",
            "Principal": {
                "Service": "states.amazonaws.com"
            },
            "Action": [
                "kms:Decrypt",
                "kms:GenerateDataKey"
            ],
            "Resource": "<activity_kmskey_arn>",
}
```

- Customers have the option to encrypt data sent to CloudWatch Logs. To support this, if the customer provides both the `kmsKey?` and `logs?` prop, the following key policy statement will be added to the key used by the StateMachine:

```
{
            "Effect": "Allow",
            "Principal": {
                "Service": "delivery.logs.amazonaws.com"
            },
            "Action": [
                "kms:Decrypt",
            ]
}
```

In addition the execution role will be updated to include a separate policy that includes kms actions and encryption context for logging (otherwise customer will not see logs)
```
{
            "Effect": "Allow",
            "Action": [
                "kms:GenerateDataKey"
            ],
            "Resource": "<state_machine_kms_key_arn>",
            "Condition": {
                "StringEquals": {
                    "kms:EncryptionContext:SourceArn": "arn:aws:logs:<region><account_id>:*"
                }
            }
}
```

### Description of how you validated changes

### Unit Test (scenarios):
- Activity 
   - Creating an Activity with a KMS Key and without specifying `kmsDataKeyReusePeriodSeconds` defaults to 300 secs
   - Creating an Activity with a KMS Key results in the correct KMS key policy being generated which allows only the Activity to perform `'kms:Decrypt'`, `'kms:GenerateDataKey'` actions on the associated KMS key.
   - Creating an Activity with invalid `kmsDataKeyReusePeriodSeconds` throws an error
   - Creating an Activity with `AwsOwnedEncryptionConfiguration` uses `AWS_OWNED_KEY` encryption type.
- StateMachine 
  - Creating a State Machine with a KMS Key allows only StateMachine execution role to perform `'kms:Decrypt'`, `'kms:GenerateDataKey'` actions on the key.
  - Creating a State Machine with `logs?` and `kmsKey?`:
    -  Separate IAM policy statement (using encryption context for logging) being generated for the State Machine execution role
    -  KMS key policy statement which enables log service delivery for integrations
  - Creating a State Machine which invokes an Activity using KMS encryption results in a IAM policy generated which allows the execution role to perform `'kms:Decrypt'`, `'kms:GenerateDataKey'` actions on the Activity KMS key
  - Creating a StateMachine with a KMS Key and without specifying `kmsDataKeyReusePeriodSeconds` defaults to 300 secs
  - Creating a State Machine with a KMS key and *invalid* `kmsDataKeyReusePeriodSeconds` throws a validation error
  - Creating a StateMachine with `AwsOwnedEncryptionConfiguration` uses `AWS_OWNED_KEY` encryption type.

 
### Integration tests
 - Create a State Machine and Activity which both have encryption enabled and assert the activity input is correct when calling `getActivityTask` API
 - Create a State Machine with encryption and logging enabled. Ensure _decrypted_ logs are being pushed to the log group. 
 

### Code samples
 - #### Creating an Activity with Encryption using a Customer Managed Key
```typescript
const kmsKey = new kms.Key(this, 'Key');
const activity = new sfn.Activity(this, 'ActivityWithCMKEncryptionConfiguration', {
  activityName: 'ActivityWithCMKEncryptionConfiguration',
  encryptionConfiguration: new sfn.CustomerManagedEncryptionConfiguration(kmsKey, cdk.Duration.seconds(75))
});
```

 - #### Creating a StateMachine with Encryption using a Customer Managed Key
```typescript
const kmsKey = new kms.Key(this, 'Key');
const stateMachine = new sfn.StateMachine(this, 'StateMachineWithCMKEncryptionConfiguration', {
  stateMachineName: 'StateMachineWithCMKEncryptionConfiguration',
  definitionBody: sfn.DefinitionBody.fromChainable(sfn.Chain.start(new sfn.Pass(this, 'Pass'))),
  stateMachineType: sfn.StateMachineType.STANDARD,
  encryptionConfiguration: new sfn.CustomerManagedEncryptionConfiguration(kmsKey, cdk.Duration.seconds(60)),
});
```

- #### Creating a StateMachine with CWL Encryption using a Customer Managed Key
``` typescript
const stateMachineKmsKey = new kms.Key(this, 'StateMachine Key');
const logGroupKey = new kms.Key(this, 'LogGroup Key');

// Required KMS key policy to enrypt the CloudWatch log group
logGroupKey.addToResourcePolicy(new cdk.aws_iam.PolicyStatement({
  resources: ['*'],
  actions: ['kms:Encrypt*', 'kms:Decrypt*', 'kms:ReEncrypt*', 'kms:GenerateDataKey*', 'kms:Describe*'],
  principals: [new cdk.aws_iam.ServicePrincipal(`logs.${cdk.Stack.of(this).region}.amazonaws.com`)],
  conditions: {
    ArnEquals: {
      'kms:EncryptionContext:aws:logs:arn': cdk.Stack.of(this).formatArn({
        service: 'logs',
        resource: 'log-group',
        sep: ':',
        resourceName: '/aws/vendedlogs/states/MyLogGroup',
      }),
    },
  },
}));

const logGroup = new logs.LogGroup(this, 'MyLogGroup', {
  logGroupName: '/aws/vendedlogs/states/MyLogGroup',
  encryptionKey: logGroupKey,
});

const stateMachine = new sfn.StateMachine(this, 'StateMachineWithCMKWithCWLEncryption', {
  stateMachineName: 'StateMachineWithCMKWithCWLEncryption',
  definitionBody: sfn.DefinitionBody.fromChainable(sfn.Chain.start(new sfn.Pass(this, 'PassState', {
    result: sfn.Result.fromString('Hello World'),
  }))),
  stateMachineType: sfn.StateMachineType.STANDARD,
  encryptionConfiguration: new sfn.CustomerManagedEncryptionConfiguration(stateMachineKmsKey)
  logs: {
    destination: logGroup,
    level: sfn.LogLevel.ALL,
    includeExecutionData: true,
  },
});
```

### Checklist
- [X] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: VaidSaraswat