Support for multi-batch processing in torchsearchsorted

[mihaimorariu]

The implementation of torchsearchsorted that is currently being used does not support multi-batch processing. A for loop in currently being used in NeRF training for handling a batch size larger than one, but that significantly slows down the training process. This needs to be fixed.

Tasks to be completed

• [ ] TODO

Definition of Done Training NeRF with batch size > 1 yields similar PSNR on the evaluation set after removing the for loop and replacing it with a multi-batch-based torchsearchsorted.