Automatic Lip Reading Recognition (ALR) - ASR/CV (Visual ASR)
# What does this PR do ?

Add a new "cv" branch for lip reading task and everything related to computer vision

**Collection**: cv

# Changelog 
- new cv branch
- 6 new cv models in cv/models: VisualEncDecCTCModelBPE, VisualEncDecCTCModel, VisualEncDecHybridRNNTCTCBPEModel, VisualEncDecHybridRNNTCTCModel, VisualEncDecRNNTBPEModel, VisualEncDecRNNTModel
- cv datasets in cv/data: VideoToBPEDataset, VideoToCharDataset, TarredVideoToBPEDataset
- cv modules in cv/modules: ResNetVideoFrontEnd, LinearProjectionVideoFrontEnd, VideoAugmentation, VideoPreprocessor
- video featurizer in cv/parts/preprocessing

# Usage
* You can potentially add a usage example below

```python
import nemo.collections.cv as nemo_cv
from omegaconf import OmegaConf

config_path = "model_config.yaml"
params = OmegaConf.load(config_path)

# hybrid CTC/RNN-T BPE lip reading model
model = nemo_cv.models.VisualEncDecHybridRNNTCTCBPEModel(cfg=params.model)

```

# Before your PR is "Ready for review"
**Pre checks**:
- [ ] 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
- [ ] 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)
