L2 constructs for CodeArtifact

[alternatejay]

Description

Create L2 constructs for CodeArtifact. Currently only the autogenerated Cfn Constructs are exposed, making work on CodeArtifact repositories and domains tedious.

Here are a few existing issues that have touched on these:
aws/aws-cdk#11131 (open)
aws/aws-cdk#11090 (stalled, closed)

I've taken the code branch from issue 11090 and gotten it working with aws-cdk-lib at https://github.com/alternatejay/aws-cdk/tree/contrib/codeartifact-l2 as a starting point, so it would great to see what is workable here. I'll be linking this issue in the other threads for visibility as well.

Roles

Role	User
Proposed by	@alternatejay
Author(s)	@alternatejay
API Bar Raiser	@alias
Stakeholders	@alias, @alias, @alias

See RFC Process for details

Workflow

• Tracking issue created (label: status/proposed)
• API bar raiser assigned (ping us at #aws-cdk-rfcs if needed)
• Kick off meeting
• RFC pull request submitted (label: status/review)
• Community reach out (via Slack and/or Twitter)
• API signed-off (label status/api-approved applied to pull request)
• Final comments period (label: status/final-comments-period)
• Approved and merged (label: status/approved)
• Execution plan submitted (label: status/planning)
• Plan approved and merged (label: status/implementing)
• Implementation complete (label: status/done)

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Author is responsible to progress the RFC according to this checklist, and
apply the relevant labels to this issue so that the RFC table in README gets
updated.