Previously, some judgement results were not reverted
when the source DHO is not alive (e.g. frames skipped in editor).
Now, all results are reverted in the exact reverse order.
Now, `OnAdd` is always invoked after the DHO is added to the container.
This change is required by `ScrollingHitObjectContainer` to compute origin adjusted lifetime when origin position is relative to the parent drawable size.
Previously, non-pooled DHOs were immediately added as children of the HOC when Add is called. Also, non-pooled DHOs were always attached to the HOC as children.
New behavior is that non-pooled DHOs are only added after CheckChildLifetime, and only attached to the HOC while the DHOs are alive.
- LifetimeManagementContainer inheritance of HOC is removed, as it is now all DHOs are "unmanaged" (previously `AddInternal(false)`).
- The signature of `Clear` is changed, and it is now always not disposing the children immediately.
`DrawableHitObject.OnKilled()` calls `UpdateResult()` to clean up a
hitobject's state definitively with regards to the judgement result
before returning the DHO back to the pool.
As it turns out, if a consumer was relying on this code path (as taiko
was in the case of nested strong hit objects), it would not work
properly with pooling, due to `HitObjectContainer` unsubscribing from
`On{New,Revert}Result` *before* calling the DHO's `OnKilled()`.
This in turn would lead to users potentially getting stuck in gameplay,
due to `ScoreProcessor` not receiving all results via that event path.
To resolve, change the call ordering to allow hit result changes applied
in `OnKilled()` to propagate normally.
