If the skin is changed before gameplay has started (at the loading
screen) it is possible for a sequence of events to occur which results
in the animation not being played:
- `SkinReloadableDrawable` runs its BDL load (and calls `OnSkinChanged`
once)
- User changes skin, triggering `DrawableJudgement`'s skin change
handling (binding directly on the `SkinSource` locally)
- This will call `PrepareDrawables` and reinitialise the
`SkinnableDrawable` child hierarchy, then immediately apply the
animations to it.
- The new `SkinnableDrawable` will then get the `SkinChanged` event and
schedule a handler for it, which will run on its first Update call.
- Any added animations will be lost as a result.
Fixed by binding directly to the `SkinnableDrawable`'s `OnSkinChanged`.
This has the added bonus of not needing to reinitialise the child
hierarchy on skin change (which felt a bit weird in the first place).
Until now UpdateStateTransforms was applying results offsets to
StartTime. This didn't cover the case of a HitObject with duration,
where the call would be made with `StartTime + hitOffset` rather than
`EndTime + hitOffset`.
To resolve this, a new method has been added which should be used to
handle hit-specific state transforms.
We've seen multiple cases where DrawableHitObject are stuck in the lifetime management container
due to not implementing a judgement (meaning they are never "hit" or "missed"). To avoid this going forward
CreateJudgement() must be implemented and return a non-null judgement.
This fixes BananaShower and JuiceStreams in osu!catch.
This also makes HitObject abstract and cleans up convert HitObject implementations.
