Add ability to `charmcraft close` not supported base.

[taurus-forever]

What needs to get done

Hi,

At the moment users can close [track/]risk[/branch] only.

However one channel/track usually has several bases, some might be deprecated or just garbage. It is a feature request to close the specific base only.

Example, see the charm https://charmhub.io/data-platform-libs :

> charmcraft status data-platform-libs
Track    Base                  Channel    Version    Revision                                                                                                                                                                                          
latest   ubuntu 20.04 (amd64)  stable     2          2                                                                                                                                                                                                 
                               candidate  ↑          ↑                                                                                                                                                                                                 
                               beta       ↑          ↑                                                                                                                                                                                                 
                               edge       9          9                                                                                                                                                                                                 
         ubuntu 22.04 (amd64)  stable     54         54                                                                                                                                                                                                
                               candidate  81         81                                                                                                                                                                                                
                               beta       ↑          ↑                                                                                                                                                                                                 
                               edge       81         81    

The base 20.04 is not updated for many years and was the earlier experiments, garbage at the moment. We should like to hide/remove/close it to avoid users confusing. Unfortunately, it is not currently possible, we can close the whole track/risk[/branch] only.

Q2: BTW, can I close the whole track latest and then push base 22.04 only (to reopen latest). Will 20.04 re-appear in this case?

Tnx!

Why it needs to get done

See the example above: to clean early experimental bases in the actively supported track.

[lengau]

For question 1, I've made a store request that would be dependent on this: https://bugs.launchpad.net/snapstore-server/+bug/2088469

For #2, I don't know, but I'll ask someone on the store team to weigh in here.

[milos-lukic]

To answer #2 - 20.04 shouldn't re-appear in that case. After closing only the newly released revisions should be present.

[taurus-forever]

re #2 - confirmed. After the close/re-release the 20.04 has gone:

Thank you!