Fix song select rewind logic not handling deleted beatmaps

[Renzo904]

When you rewind to a deleted beatmap, the game still selects the deleted beatmap, glitching the carousel, now it should check if the beatmap to rewind exists within beatmapSets
Before:

[bdach]

Please add test coverage for the bugged scenario in this pull request. See TestSceneBeatmapCarousel.TestRandom() for inspiration.

[bdach]

Should probably not be checking all beatmaps like that and be doing

Suggested change

	if (!beatmap.Filtered.Value && beatmapSets.Any(beatset => beatset.Beatmaps.Contains(beatmap)))
	if (!beatmap.Filtered.Value && beatmap.BeatmapSet?.PendingDelete != false)

instead.

[frenzibyte]

The only way to access the PendingDelete flag would be by: beatmap.BeatmapInfo.BeatmapSet.PendingDelete. And apparently, that doesn't look to get updated when the beatmap is actually deleted.

I've went with a different solution that's still magnitudes more efficient than iterating through all beatmaps in the carousel.

[peppy]

probably okay

[LittleEndu]

Switch from stack to list wasn't handled correctly. Rewind now selects the last beatmap from list but removes the first instance from the list, so if there are multiple instance of the same beatmap, rewind will keep selecting the same beatmap until all instances are removed. Easy to reproduce if you search for something that returns 5 or so beatmaps, use random 15 times, rewind will select each beatmap 3 times before selecting the next in list.

[bdach]

@LittleEndu can you open an actual issue please thanks