Mutiscale Diarization Decoder (MSDD) model and module files
Signed-off-by: Taejin Park <tango4j@gmail.com>

# What does this PR do ?

Add multiscale diarization decoder model module, and yaml files. 
Additionally, yaml files are also uploaded.

- msdd_models.py

Three classes are included:
(1) ClusterEmbedding
This class is for taking care of cluster-average embeddings by launching clustering diarizer class.
The methods in this class read embedding vectors and clustering output that are written from clustering diarizer class.

(2) EncDecDiarLabelModel
MSDD model class.

(3) OverlapAwareDiarizer
A class that launches Clustering Diarizer and run MSDD infer then evaluate it.
It involves integration of pairwise inference from MSDD and split-infer that breaks down the input to
short sequences.

- msdd_diarizer.py
MSDD Neural model class. 

- speaker_utils.py
audio_rttm_map() function is modified to deal with the uniq_id with duration information.

-audio_to_diar_label.py, collections.py

These are couple of very small points where it needs to be changed like: rttm_files -> audio_files 
(We need to extract uniq_id when rtttm is not provided for evaluation)

- 4 x yaml files
msdd_5scl_15_05_50Povl_infer.yaml -> for inference
msdd_6scl_30_05_50Povl_infer.yaml -> for inference
msdd_5scl_15_05_50Povl_256x3x32x2.yaml  -> for training 
msdd_6scl_30_05_50Povl_256x3x32x2.yaml  -> for training 

The name of these files are up for debate.

* Tutorial and script for training data generation is excluded since it makes PR too big.


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

# Changelog 
- Add specific line by line info of high level changes in this PR.

# Usage
* Use the following command to run MSDD.
```python
HYDRA_FULL_ERROR=1 python $BASEPATH/multiscale_diar_decoder_infer.py
 --config-path='conf' --config-name='msdd_5scl_15_05_50Povl_infer.yaml' \
    diarizer.manifest_filepath=<TEST_MANIFEST> \
    diarizer.out_dir=<TEST_EMB_DIR> \
    diarizer.msdd_model.model_path=<MSDD_MODEL_PATH>\
```

# 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? - Added unitest for msdd_model. Will add unit-test for audio_to_diar_label once micro diarization dataset is ready.
- [ ] 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.

# Additional Information
* Related to # (issue)
