feat: Add support for retrieving DateTime attributes in UTC timezone from a DynamoDB table

[96malhar]

Description

This PR adds support for retrieving DateTime attributes in UTC timezone from a DynamoDB table.

While working in the data model mode, this PR introduces a boolean flag called RetrieveDateTimeInUtc as part of the DynamoDBContextConfig as well as the global AWSConfigsDynamoDB.Context. If set to true, then all DateTime attributes are retrieved in the UTC timezone.

While working in the document model mode, Each Document object stores attributes as a DynamoDBEntry. The SDK already has the AsDateTime virtual method that is used to convert a DynamoDBEntry to a DateTime object. This PR also introduces a AsDateTimeUtc method to retrieve all DateTime attributes in the UTC timezone.

Motivation and Context

Fixes #1450 and DOTNET-7259

Testing

Added new unit and integration tests.
Successful dry-run (build-id: 39a8ce27-a0db-4976-8ee4-5bd6f6a41004 and 693449ba-8bf6-4280-bf21-fc8ec0bdf2d3)

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