* support for true batches with multipack
* patch the map dataset fetcher to handle batches with packed indexes
* patch 4d mask creation for sdp attention
* better handling for BetterTransformer
* patch general case for 4d mask
* setup forward patch. WIP
* fix patch file
* support for multipack w/o flash attention for llama
* cleanup
* add warning about bf16 vs fp16 for multipack with sdpa
* bugfixes
* add 4d multipack tests, refactor patches
* update tests and add warnings
* fix e2e file check
* skip sdpa test if not at least torch 2.1.1, update docs