`IconButton` with `variant="invisible"` has non-invisible `disabled` styling

[iansan5653]

IconButton's invisible variant renders the button as a simple icon with no border. However, if you then apply disabled to that button, a border appears. The result is distracting changes (border and background) as buttons switch from disabled to enabled and back:

The effect of this can be seen in practice in the comment editor toolbar when submitting issue comments:

Screen.Recording.2024-12-12.at.10.54.32.AM.mov

I would expect disabled versions of invisible buttons to just be the same styling but with a slight fade-out (ie, translucency).

[siddharthkp]

Hi! I talked to @langermank about this and she's happy to accept a PR. I might try to create on tomorrow unless you want to race me on it 😄

(note: need to update both js and module.css styles)

cc @francinelucca

[iansan5653]

unless you want to race me on it

🐎 #5423

note: need to update both js and module.css styles

As far as I can tell from the code, the JS styles have already been removed and CSS modules is globally shipped for buttons. I could be wrong though

[langermank]

Addressed via #5440