Pkg3: Quality Tags (unstable/testing/candidate/stable)

It would be useful to have a facility for applying mutable quality tags to a release.
e.g.
- Make a quick-fix for a user-reported bug, push a release to the registry, tagged "testing".
- Ask the user to try out the fix.
- Wait for the CI results for the release and all the dependant packages.
- If all is well, a few days later tag the release as "stable".
or:
- Do some kind of major refactoring and push out a release tagged "unstable".
- After a period of beta testing, push out a new release tagged "testing" (or "candidate")
- etc...

Maybe users could push releases into the registry without waiting for human review, but only official reviewers would be allowed to apply the "released" tag?

End users could configure their production environment to only run "stable" packages and their playing-with-new-stuff environment to run anything.

REQUIRES files could include quality tag qualifiers.

Perhaps in the future there could be a "certified" tag that indicates a quality review has been done by an approved body.