Among others, this features a scary-looking change wherein
`WorkingBeatmap` now exposes a `RealmAccess` via
`IStorageResourceProvider`. This is necessary to make
`RealmBackedResourceStore` actually start firing callbacks when the
edited beatmap's skin is modified by adding new samples to it.
`dotnet format` expects me to put a space between the spread `..` and
the expression after which is UTTERLY STUPID AND UGLY AND WRONG AND
CANNOT BE `.editorconfig`'d BECAUSE [INSERT EXCESSIVELY LONG BLEEP].
God I hate when good features are kneecapped by this sort of stupidity.
The test scene doesn't exercise the custom sample playback, but I hope I
can be forgiven for this as setting up a custom editor beatmap just for
this to work is rather cumbersome.