Use the Packages API to search for a package using metadata

Problem to solve

You use the GitLab Package Registry to publish, share and install packages alongside your source code and pipelines. During a build, you'd like to be able to find a specific package so that you can use it throughout the rest of your build. You can use the Packages API to find packages in your project or group using: package_type, package_name, and status.

But for those of you that have many thousands of packages in your registry, this might not be precise enough. You really need to be able to filter your results based on key metadata for each package.

Proposal

Expand the list packages API by supporting additional search attributes for metadata related to the package, including:

1. Version
2. Git tag
3. Hash values
4. Metadata included in the package definition.

Note - since the last item varies based on format, we'll need to think carefully about what to include.