Better indicate plugin development and maintenance state through labels

[csadorf]

We could use labels such as PyPI download statistics and moderated categories such as common-workflows to better indicate the development and maintenance state of a plugin in the registry.

Related to #143 .

[ltalirz]

Happy to accept a PR for integrating PyPI download statistics.

As for other discoverability, there is https://github.com/aiidateam/aiida-registry/issues/215 which I haven't had time to come back to. It works locally, just not on github actions, and it would give us access to detailed information of the workflows every plugin provides.

I think a page with more details on the available workflows will be a great way for newcomers to discover & browse through available capability.

[ltalirz]

The sorting by commits in the past year #245 is a good step into this direction (as is the sorting by most recent release). Closing this for the moment; feel free to reopen with new ideas