feat: recommend Snapcraft 9.x for core22, core24, and core26 bases

[rizqiamad]

Description

Add a warning message recommending Snapcraft 9.x when building
snaps with core22, core24, or core26 bases.

Closes #4958

• I've followed the contribution guidelines.
• I've signed the CLA.
• I've successfully run make lint && make test.
• I've added or updated any relevant documentation.
• In documents I changed, I added a meta description if one was missing.
• I've updated the relevant release notes.

[mr-cal]

Thanks, @rizqiamad!

The code itself looks good, this is just a matter of the message presentation.

[mr-cal]

This is my suggestion, but let's wait for feedback from @canonical/starcraft-authors:

Suggested change

	f"Base {base!r} is supported in Snapcraft 9.x. "
	"It is recommended to upgrade to Snapcraft 9.x via the 'latest/stable' channel "
	"to benefit from the latest bug fixes and performance improvements."
	f"Snapcraft 9 is recommended for {base!r}. "
	"Upgrade to Snapcraft 9 for the latest bug fixes and improvements."

[rizqiamad]

Sure! I'll wait for feedback from @canonical/starcraft-authors first.
Please let me know once there's a decision, as the test file will need
to be updated as well.

[medubelko]

The format looks good, with some things to consider:

• "update" might be better than "upgrade", since the latter can suggest more of a toll for the user.
• Wildcard: how would you feel about "refresh" to match the command name?
• I would go with "features and improvements".

[mr-cal]

Can you switch this to emit.warning?

[rizqiamad]

Sure! I checked and emit.warning is available in craft-cli. I'll switch it now

[bepri]

Assuming @mr-cal's feedback is taken, I'm happy with the code as well, so I'll go ahead and approve now :)

@mr-cal Just out of curiosity, this doesn't get merged back into main right? Or does the commit go in and we just add another commit to remove it again?

[mr-cal]

Assuming @mr-cal's feedback is taken, I'm happy with the code as well, so I'll go ahead and approve now :)

@mr-cal Just out of curiosity, this doesn't get merged back into main right? Or does the commit go in and we just add another commit to remove it again?

Yes to the latter - we can merge the commit but either undo it with a new commit or undo as part of the merge-commit itself.

I like undoing as part of the merge-commit because the history looks cleaner.