Make LabelsInput accept container's size

[bl-nero]

This helps sizing it properly in contexts like the role editor. Also: replace the trash can icon with a cross icon.

This PR changes the internal structure of LabelsInput from a bunch of boxes to a regular table, which is also more accessible.

Before:

After:

Notes:

1. We still have two separate components for handling labels; unifying these is not in the scope of this PR.
2. One of the issues with the current role editor UI is that the add label buttons are too big, but I'll solve it separately, with a PR spanning multiple components; having bigger button is less jarring than having inconsistent sizes.

Contributes to #52221
Contributes to #52222

[ravicious]

This PR changes the internal structure of LabelsInput from a bunch of boxes to a regular table, which is also more accessible.

Does it mean that tables are inherently more accessible in this scenario? I didn't know about this, but I wouldn't mind reading up on it, do you have any good resources on this?

[bl-nero]

Yes, they are better. Though I don't have any actual reading material that I could recommend, let me jus prove my case with a demo of how Apple's own VoiceOver reads our UI. It would be even better to use a grid role for this, as this is an interactive table, but that would, by convention, require us to implement a different keyboard navigation scheme, so I didn't do it. Table, however, was a low-hanging fruit here, since I already needed to rebuild the layout anyway.

[ravicious]

Thanks for the recording!

[backport-bot-workflows]

@bl-nero See the table below for backport results.

Branch	Result
branch/v16	Failed
branch/v17	Create PR

[bl-nero]

(Dropping v16 backport: too complex, not worth it.)