[Skeleton Animation] Fix

[T-rvw]

1. No Idle/Walk/... enums. Read animation track names from Asset data dynamically to display how many kinds of tracks are OK to run.
2. TestAssets\Animation\Praying_NotEmbed\Praying_NotEmbed.fbx failed to parse bones due to bind poses parse error.
3. Refact SkeletonRenderer. Current status is a draft.