[ECR][CodeArtifact Integration]: It would be great if ECR would offer CodeArtifact integration

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**Tell us about your request**
It would be great if ECR could be integrated with CodeArtifact so that CodeArtifact could become a "one-stop shop" repository. After all, Docker is a bit special, but its registry is still a repository of binaries and metadata, much like NPM, Maven, Nuget, Pypi, etc.

The main CodeArtifact/ECR competitors already have this feature (they've had it for almost half a decade each, I believe):

Artifactory: https://jfrog.com/artifactory/features/
Nexus: https://www.sonatype.com/products/repository-pro

**Which service(s) is this request for?**
ECR

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
We'd like to have a single point to manage all our binary repositories, including Docker.

**Are you currently working around this issue?**
Separate CodeArtifact and ECR repositories. Extra administrative effort, extra permissions, the works.

Start by reviewing the ECR and CodeArtifact service documentation and the integration capabilities described in this request. Define the required repository behavior, permissions, and Docker artifact flow; done would mean users can manage Docker images alongside other binary repositories through a single CodeArtifact-centered experience.

Written by the indexing model from the issue text.