[refactor] CogVideoX followups + tiled decoding support (#9150)
* refactor context parallel cache; update torch compile time benchmark
* add tiling support
* make style
* remove num_frames % 8 == 0 requirement
* update default num_frames to original value
* add explanations + refactor
* update torch compile example
* update docs
* update
* clean up if-statements
* address review comments
* add test for vae tiling
* update docs
* update docs
* update docstrings
* add modeling test for cogvideox transformer
* make style