Add VideoMAE video processor (#41534)
* Add video processor for VideoMAE
* Document VideoMAE video processor
* Add regression tests for VideoMAE video processor
* refactor: Use direct batch key access for pixel_values_videos
* test: add parity test for VideoMAEVideoProcessor vs VideoMAEImageProcessor
* docs(videomae): update model docstring example to demonstrate VideoMAEVideoProcessor (TorchCodec-based decoding and sampling)
