Boostrapping + Create, List, and Read Handlers for AWS::CodeArtifact::Domain

[jonjara]

Issue #, if available:

Description of changes:

This PR has

• the initial boostrapping AWS::Codeartifact::Domain Resource handlers
• Implementation of Create, Read, List handlers

Testing Unit tests and I ran cfn invoke CREATE sam-tests/create_payload.json cfn invoke DELETE sam-tests/delete_payload.json cfn invoke LIST sam-tests/create_payload.json

and submitted the resource and create a domain with a cloudformation stack, testing

• Create Stack with/without PolicyText
• Update Stack with Domain policy
• Update Stack while removing policy
• Deleting Stack

Please see the latest commit to see a diff of changes I wrote

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