Set IsDeleteMarker to true when unmarshalling delete markers

[peterrsongg]

Description

Pre S3 code-gen we were setting IsDeleteMarker to true when unmarshalling delete markers for ListVersions. I missed this in the custom code here: https://github.com/aws/aws-sdk-net/blob/main/sdk/src/Services/S3/Custom/Model/Internal/MarshallTransformations/ListVersionsResponseUnmarshaller.cs#L33-L41

Here is what it was set to pre code gen

aws-sdk-net/sdk/src/Services/S3/Custom/Model/Internal/MarshallTransformations/ListVersionsResponseUnmarshaller.cs

Lines 117 to 128 in 79cbc39

	if (context.TestExpression("DeleteMarker", targetDepth))
	{
	if (response.Versions == null)
	{
	response.Versions = new List<S3ObjectVersion>();
	}
	var version = VersionsItemUnmarshaller.Instance.Unmarshall(context);
	version.BucketName = response.Name;
	version.IsDeleteMarker = true;
	response.Versions.Add(version);
	continue;

Motivation and Context

Testing

dry run in progress

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed

License

• I confirm that this pull request can be released under the Apache 2 license