RFC. Closes https://github.com/ppy/osu/issues/27883.
The idea here is that `PopOut()` is called _when the hide is requested_,
so once an overlay trigger would hide, the overlay would
`StopAnyPlaying()`, but because of async load things, the actual track
would start playing after that but before the overlay has fully hidden.
(That last part is significant because after the overlay has fully
hidden, schedules save the day.)
Due to the loose coupling between `PreviewTrackManager` and
`IPreviewTrackOwner` there's really no easy way to handle this locally
to the usages of the preview tracks. Heck, `PreviewTrackManager` doesn't
really know which preview track owner is to be considered _present_ at
any time, it just kinda works on vibes based on DI until the owner tells
all of its preview tracks to stop.
This solution causes the preview tracks to stop a little bit later but
maybe that's fine? Just trying to not overthink the issue is all.
No tests because this is going to suck to test automatically while it is
pretty easy to test manually (got it in a few tries on master).
The issue also mentions that the track can sometimes resume playing
after the overlay is pulled up again, but I don't see that as a problem
necessarily, and even if it was, it's not going to be that easy to
address due to the aforementioned loose coupling - to fix that, play
buttons would have to know who is the current preview track owner and
cancel schedules upon determining that their preview track owner has
gone away.
Closes https://github.com/ppy/osu/issues/27549.
I'm not entirely sure why the old solution failed exactly, but also
think it's unimportant because I think past me was an idiot and was
playing stupid games with the juggling of indices between two callbacks
with no ordering guarantees and expecting not to win stupid prizes.
I'm not sure this requires any follow-up reconsiderations of that entire
text flow API, but if opinions differ, I'll re-examine.
Starting from the end (which should be fine with the current number of columns, even on different/wider screen resolutions), and with a custom decay value when it reaches zero offset.
