Add silence handling for speaker diarization pipeline
Signed-off-by: nithinraok <nithinrao.koluguri@gmail.com>

# What does this PR do ?

Provides fix for handling silence wav files for diarization

**Collection**: [ASR - Speaker Diarization]

# Changelog 
- Added `validate_vad_manifest` function to compare the uniq_ids in vad manifest file to manifest file provided by user for diarization
- Fixed an issue to check for a VAD `.frame` file, even if the duration of that audio is <=0. 

# Usage

```bash
python offline_diarization.py
```

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- [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?
- [ ] 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**:
- [ ] New Feature
- [x] Bugfix
- [ ] Documentation
