Add option for mutex timeout in distributed optimizer backward hook
Could we replace `self._lock` itself with the timeout-enabled one? The parent Apex distributed optimizer class also uses `self._lock`  (e.g., [here](https://github.com/NVIDIA/apex/blob/master/apex/contrib/optimizers/distributed_fused_adam.py#L832)) and we want to catch those as well if they take too long. Testing a modified version in this draft PR: https://github.com/NVIDIA/NeMo/pull/9087 This PR is stale because it has been open for 14 days with no activity. Remove stale label or comment or update or this will be closed in 7 days. This PR was closed because it has been inactive for 7 days since being marked as stale.
# What does this PR do ?

This is to help debug a hang at https://github.com/NVIDIA/NeMo/blob/f658b6f0445403c338c7371941b1fe644832df48/nemo/core/optim/distributed_adam.py#L131

Add a one line overview of what this PR aims to accomplish.

**Collection**: NLP

# Changelog 
- Add option for mutex timeout in distributed optimizer backward hook

# Usage

Run GPT, e.g. with the config at https://github.com/NVIDIA/NeMo/blob/main/examples/nlp/language_modeling/conf/megatron_gpt_config.yaml.

Enable the distributed optimizer with `model.optim.name=distributed_fused_adam` and set the timeout with `model.optim.lock_timeout=<seconds>`.

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