Summary:
- Make arrow iterator able to read from jsonl files, the entropies are omitted in this case
- Make the data/checkpoint code fsspec compatible
- Fix issues with all reduce with non-bf16 in dist_sum and norm computation.
- Minimal fixes to get eval to run, it is slow currently
- Add bpb numbers during training
Test Plan:
Run unit tests and the commands below
```
python -m bytelatent.train config=internal/configs/s3_debug.yaml eval=null checkpoint.dump.every=100
```
```
torchrun --nproc-per-node 8 -m bytelatent.train config=internal/configs/s3_debug.yaml eval=null checkpoint.dump.every=100
```
```
python -m bytelatent.train config=internal/configs/s3_debug.yaml eval=null checkpoint.dump.every=100 dump_dir=s3://blt/scratch/checkpoint-test/
```
```
torchrun --nproc-per-node 8 -m bytelatent.train config=internal/configs/s3_debug.yaml eval=null checkpoint.dump.every=100 dump_dir=s3://blt/scratch/checkpoint-test/
```
