DynamoDB XSPEC SDK for Java SDK 2.0

### Describe the feature

AWS Java SDK v1 supports DynamoDB xspec API.
Blog here: https://aws.amazon.com/blogs/developer/dynamodb-xspec-api/

Can't find the equivalent in aws-sdk-java-v2 code base.

### Is your Feature Request related to a problem?

The XSPEC API offers a convenient layer on top of DynamoDB. Nice to have.

### Proposed Solution

Add relevant code from [here](https://github.com/aws/aws-sdk-java/tree/fd409dee8ae23fb8953e0bb4dbde65536a7e0514/aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/xspec) and [here](https://github.com/aws/aws-sdk-java/tree/fd409dee8ae23fb8953e0bb4dbde65536a7e0514/aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/document/spec) to SDK 2.0 or provide another package that may wrap on top of the low level SDK.

### Describe alternatives you've considered

_No response_

### Acknowledge

- [ ] I may be able to implement this feature request

### AWS Java SDK version used

2.0

### JDK version used

Java 11

### Operating System and version

All