feat(ec2): adding placementGroup to LaunchTemplateProps and LaunchTemplate (#33726)

### Issue # (if applicable)

Closes #33721

### Reason for this change

To allow for passing `PlacementGroup`s to `LaunchTemplate`s


### Description of changes

Adding `placementGroup` to `LaunchTemplateProps`. I chose to only implement this part of the `placement` field in LaunchTemplates, not doing anything with dedicated hosts or the like, as those don't have any CDK constructs. This change enables creating a `PlacementGroup` and passing it to a `LaunchTemplate`

### Describe any new or updated permissions being added

None


### Description of how you validated changes

Added a unit test, ran the existing tests as well.

### 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: clayrosenthal

Diff for: packages/@aws-cdk-testing/framework-integ/test/aws-ec2/test/integ.launch-template.js.snapshot/LambdaTestDefaultTestDeployAssert1AF2B360.assets.json

@@ -284,6 +284,58 @@
      }
     ]
    }
+  },
+  "pg749EE6ED": {
+   "Type": "AWS::EC2::PlacementGroup",
+   "Properties": {
+    "Strategy": "spread"
+   }
+  },
+  "LTWithPlacementGroup4B40027C": {
+   "Type": "AWS::EC2::LaunchTemplate",
+   "Properties": {
+    "LaunchTemplateData": {
+     "Placement": {
+      "GroupName": {
+       "Fn::GetAtt": [
+        "pg749EE6ED",
+        "GroupName"
+       ]
+      }
+     },
+     "TagSpecifications": [
+      {
+       "ResourceType": "instance",
+       "Tags": [
+        {
+         "Key": "Name",
+         "Value": "aws-cdk-ec2-lt-metadata-1/LTWithPlacementGroup"
+        }
+       ]
+      },
+      {
+       "ResourceType": "volume",
+       "Tags": [
+        {
+         "Key": "Name",
+         "Value": "aws-cdk-ec2-lt-metadata-1/LTWithPlacementGroup"
+        }
+       ]
+      }
+     ]
+    },
+    "TagSpecifications": [
+     {
+      "ResourceType": "launch-template",
+      "Tags": [
+       {
+        "Key": "Name",
+        "Value": "aws-cdk-ec2-lt-metadata-1/LTWithPlacementGroup"
+       }
+      ]
+     }
+    ]
+   }
   }
  },
  "Mappings": {