NeMo Forced Aligner
Signed-off-by: Elena Rastorgueva <erastorgueva@nvidia.com>

# What does this PR do ?

Add NFA - a tool to do forced alignment using NeMo CTC-based models. 

**Collection**: [Note which collection this PR will affect]
Tools 

# Changelog 
- Add NeMo/tools/nemo_forced_aligner/

# Usage
* You can potentially add a usage example below

```bash
python $NEMO_PATH/tools/nemo_forced_aligner/align.py \
    pretrained_name="stt_en_citrinet_1024_gamma_0_25" \
    model_downsample_factor=8 \
    manifest_filepath="manifest.json" \
    output_dir="nfa_ctms/" \
    batch_size=1 \
    additional_ctm_grouping_separator="|" \
    audio_filepath_parts_in_utt_id=1

```

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

# Additional Information
* Related to # (issue)
