Added support for neptune logger
jenkins Hi @titu1994 what would be the next process to get this merged to the main trunk ? Could you avoid merging the main branch with this PR, I need to see the tests pass. It is fine if the branch is out of date with the main branch.  jenkins > jenkins

I guess the automation is completed and all checks have passed.
@titu1994 
# What does this PR do ?

Adds Neptune logging support to NeMo which is already exposed by the PTL trainer.

**Collection**: Core, NLP

# Changelog 
- In experiment manager, consumed NeptuneLogger parameters from the OmegaConf
- Added tests for NeptuneLogger
- Added documentation for NeptuneLogger configuration


# Usage
* Can be directly used by configuring the mentioned keys in the docs under exp_manager similar to how WandB params are specified.

```python
# Add a code snippet demonstrating how to use this 
```

# Jenkins CI
To run Jenkins, a NeMo User with write access must comment `jenkins` on the PR.

# 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)
- [x] Did you write any new necessary tests?
- [x] Did you add or update any necessary documentation?
- [ ] 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.

@titu1994 

# Additional Information
* Related to # (issue)
