- adding pysimdjson as a requirement for memory-efficient and fast json parsing
- added DynamicDataset class intended for jsonlines, leveraging TF's TextLineDataset C++ io as an iterator.

- Adds dynamic chunking through token cache implementation, adding overflow tokens from tokenized examples into a token cache, which gets filled first in the next call.

- Every example added to token_cache is appended by tokenizer.eos_token_id

- Removes implicit padding unless sequence falls under max_length after filling from token cache