Fix make checkbox text clickable in FileDialog

[Giganzo]

Fixes #95079

[Calinou]

Tested locally, it works as expected.

[akien-mga]

@bruvzg I see you've another draft as #95140 doing this slightly differently.
In order to (possibly) fix the regression for 4.3, do you think this approach is fine as a quick fix?

Otherwise the regression isn't critical so it's fine to have it wait.

[bruvzg]

This will immediately break for any file dialog with more than one option, it's using Grid container and should have the same number of child controls in every row.

[bruvzg]

It's not critical and I'n not sure what's the best visual way to do it (#95140 probably is not the best), so I would not do anything for 4.3.

[Giganzo]

The idea was that this could be used as a quick fix. Not sure if it still needed or if we should wait for some other solution.

[KoBeWi]

tbh the initial solution could be fine if you added an empty Control to take Label's space.

[Giganzo]

How it looks now with vbox.

tbh the initial solution could be fine if you added an empty Control to take Label's space.

With GridContainer and extra Control it looks like this.

Can revert to the GridContainer if you think it's better and this pr is still needed.

[KoBeWi]

The latter looks better, because the controls are better aligned.
However there is #97892, which might supersede this PR (it was opened independently and just happens to fix the same issue).