Support mutually recursive DynamoDB bean schemas

[afarber]

Motivation and Context

Fixes #6110.

BeanTableSchema supported direct self-references, but lost its in-progress schema cache when constructing a different nested bean type. A mutually recursive bean relationship such as Parent -> Child -> Parent therefore recursed until stack overflow.

Modifications

• Preserve the shared MetaTableSchemaCache when recursively creating nested bean schemas.
• Add a regression test covering mutually recursive @DynamoDbBean classes and a finite map round-trip.
• Correct the related internal comment.
• Add a changelog entry.

Testing

./mvnw -pl :dynamodb-enhanced -am \
  -Dtest=BeanTableSchemaRecursiveTest \
  -Dsurefire.failIfNoSpecifiedTests=false \
  -Dspotbugs.skip \
  -Dcheckstyle.skip test

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING (https://github.com/aws/aws-sdk-java-v2/blob/master/CONTRIBUTING.md) document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry.
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog
  (https://github.com/aws/aws-sdk-java-v2/blob/master/docs/LaunchChangelog.md)

License

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