Part of the screen footer refactor.
Once footer content is being managed by `OsuScreen`, the current tests
which simply create the tested overlay and `ScreenFooter` in a container
will no longer work.
This PR refactors them to use `ScreenTestScene` with the setup being
creating a dedicated testing `OsuScreen` which does the bare minimum to
create the tested overlay and necessary components (eg.
`FooterButtonFreeModsV2` for `TestSceneFreeModsOverlay`).
Most of the changes here can be described as
`%s/<...>Overlay/screen.Overlay/g`, with some minor touchups as
necessary, given that we're now testing a more complete flow which
checks more things that were previously not handled by the tests.
## [Move footer to front in
ScreenTestScene](https://github.com/ppy/osu/commit/f8740e0403b3c0badd60d394c737f2aa912a9ed6)
Self-explanatory. Without it the footer would show below the actual
overlay, breaking tests depending on manual input. For the sake of tests
not breaking in CI, both #36718 and this have this included - would
prefer the former to be merged first since it was already reviewed
there.
## `TestSceneModSelectOverlay`
There were a few tests (`TestColumnHidingOnIsValidChange`,
`TestColumnHidingOnTextFilterChange`, and
`TestHidingOverlayClearsTextSearch`) that would create a custom overlay
instance instead of the globally provided one. I've tested both and the
tests run fine with the default overlay, so they're now using that
instead.
## `TestSceneFreeModSelectOverlay`
Updated to use footer v2.
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Co-authored-by: Dean Herbert <pe@ppy.sh>
Krzysztof Gutkowski
105342e5bf