Determine need for tokenizer assets in MegatronLM checkpoints

Parent initiative: #2319

## Context

Megatron-Bridge checkpoints may include a `tokenizer/` directory containing tokenizer assets such as vocab and merges files.
It's unclear whether this should be included in the MegatronLM checkpoints.

## Task

Determine whether the tokenizer assets should be saved in MegatronLM checkpoints, and if so create a new issue with the necessary implementation requirements.

Start by reviewing parent issue #2319 and the checkpoint handling described in the issue. Compare whether Megatron-Bridge checkpoints’ tokenizer/ directory and its vocab or merges files are needed in MegatronLM checkpoints. Done means documenting the decision and, if required, creating a follow-up issue with implementation requirements.

Written by the indexing model from the issue text.