Motion Model / Adapter versatility (#8301)
* Motion Model / Adapter versatility
- allow to use a different number of layers per block
- allow to use a different number of transformer per layers per block
- allow a different number of motion attention head per block
- use dropout argument in get_down/up_block in 3d blocks
* Motion Model added arguments renamed & refactoring
* Add test for asymmetric UNetMotionModel
