Add BERT support for overlapping forward compute with distopt communication
# What does this PR do ?

This PR adds experimental support in BERT for the distributed Adam optimizer to overlap its parameter all-gather with the forward compute.

**Collection**: NLP

# Changelog 
- Add BERT support for overlapping forward compute with distopt communication

# Usage

Set the optimizer to `distributed_fused_adam` in the config file:

https://github.com/NVIDIA/NeMo/blob/a7c2a04db4375ea8669c2c8c33cb4c4c30ffabe9/examples/nlp/language_modeling/conf/megatron_bert_config.yaml#L144

Configure the optimizer with `overlap_param_sync: True`.

# Before your PR is "Ready for review"
**Pre checks**:
- [x] Make sure you read and followed [Contributor guidelines](https://github.com/NVIDIA/NeMo/blob/main/CONTRIBUTING.md)
- [ ] Did you write any new necessary tests?
- [ ] Did you add or update any necessary documentation?
- [x] Does the PR affect components that are optional to install? (Ex: Numba, Pynini, Apex etc)
  - [ ] Reviewer: Does the PR have correct import guards for all optional libraries?
  
**PR Type**:
- [x] New Feature
- [ ] Bugfix
- [ ] Documentation

If you haven't finished some of the above items you can still open "Draft" PR.


## Who can review?

Anyone in the community is free to review the PR once the checks have passed. 
[Contributor guidelines](https://github.com/NVIDIA/NeMo/blob/main/CONTRIBUTING.md) contains specific people who can review PRs to various areas.

Pinging @shanmugamr1992.

# Additional Information
* Follow-up to https://github.com/NVIDIA/NeMo/pull/5684.