feat(opensearch): Add latest Opensearch Version 1.2 (#19749)

----

### Add new OpenSearch Version 1.2

**Related Announcement**: https://aws.amazon.com/about-aws/whats-new/2022/04/amazon-opensearch-supports-version-1-2/

Upgrade option already available in AWS console.
List an example of the new version (here: 1.2) via cli in 2 different regions:
```
aws es list-elasticsearch-versions --region=eu-west-1
{
    "ElasticsearchVersions": [
        "OpenSearch_1.2",
        "OpenSearch_1.1",
        "OpenSearch_1.0",
        "7.10",
        "7.9",
       ...
   ]
}
```
or
```
aws es list-elasticsearch-versions --region=us-east-1
{
    "ElasticsearchVersions": [
        "OpenSearch_1.2",
        "OpenSearch_1.1",
        "OpenSearch_1.0",
        "7.10",
        "7.9",
       ...
   ]
}
```

### All Submissions:

* [x] Have you followed the guidelines in our [Contributing guide?](https://github.com/aws/aws-cdk/blob/master/CONTRIBUTING.md)

* [x] Did you use cdk-integ to deploy the infrastructure and generate the snapshot (i.e. cdk-integ without --dry-run)?

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

Author: T31M

packages/@aws-cdk/aws-appsync/README.md

@@ -252,7 +252,7 @@ import * as opensearch from '@aws-cdk/aws-opensearchservice';
 
 const user = new iam.User(this, 'User');
 const domain = new opensearch.Domain(this, 'Domain', {
-  version: opensearch.EngineVersion.OPENSEARCH_1_1,
+  version: opensearch.EngineVersion.OPENSEARCH_1_2,
   removalPolicy: RemovalPolicy.DESTROY,
   fineGrainedAccessControl: { masterUserArn: user.userArn },
   encryptionAtRest: { enabled: true },

packages/@aws-cdk/aws-appsync/test/integ.graphql-opensearch.expected.json

@@ -39,7 +39,7 @@
         "EncryptionAtRestOptions": {
           "Enabled": true
         },
-        "EngineVersion": "OpenSearch_1.1",
+        "EngineVersion": "OpenSearch_1.2",
         "LogPublishingOptions": {},
         "NodeToNodeEncryptionOptions": {
           "Enabled": true

packages/@aws-cdk/aws-appsync/test/integ.graphql-opensearch.ts

@@ -8,7 +8,7 @@ const app = new cdk.App();
 const stack = new cdk.Stack(app, 'appsync-opensearch');
 const user = new User(stack, 'User');
 const domain = new opensearch.Domain(stack, 'Domain', {
-  version: opensearch.EngineVersion.OPENSEARCH_1_1,
+  version: opensearch.EngineVersion.OPENSEARCH_1_2,
   removalPolicy: cdk.RemovalPolicy.DESTROY,
   fineGrainedAccessControl: {
     masterUserArn: user.userArn,

packages/@aws-cdk/aws-opensearchservice/lib/version.ts

@@ -65,6 +65,9 @@ export class EngineVersion {
   /** AWS OpenSearch 1.1 */
   public static readonly OPENSEARCH_1_1 = EngineVersion.openSearch('1.1');
 
+  /** AWS OpenSearch 1.2 */
+  public static readonly OPENSEARCH_1_2 = EngineVersion.openSearch('1.2');
+
   /**
    * Custom ElasticSearch version
    * @param version custom version number