Add conditional save, update and delete operation support for DynamoDB entities. Fixes #gh-1147

[vyomrastogi]

📢 Type of change

• Bugfix
• New feature
• Enhancement
• Refactoring

📜 Description

• Add a save(PutItemEnhancedRequest) to support item put conditionally
• Add a update(UpdateItemEnhancedRequest) to support item update conditionally
• Add a delete(DeleteItemEnhancedRequest) to support item delete conditionally

💡 Motivation and Context

At the moment DynamoDbOperation does not support conditional actions on an Entity. This would mean that developers need to get an instance of DynamoDbTable to execute lower level aws sdk methods.

The new convenience methods allow for EnhancedRequest to be executed via DynamoDbOperation.

Fixes issue #1147

💚 How did you test it?

Validated changes via Integration Tests.

📝 Checklist

• I reviewed submitted code
• I added tests to verify changes
• I updated reference documentation to reflect the change
• All tests passing
• No breaking changes

🔮 Next steps

[vyomrastogi]

Dear Reviewers,

Here I opted to make this method void as DynamoDbTable.putItem does not return updated entity. There is possibility if someone is using extensions then the entity would have been update at db layer and hence passed entity would not hold latest state.

This deviates from set norm, so happy to adapt to maintain consistency. What's your recommendation ?