Asr codeswitch
# What does this PR do ?

Enables manifest processing / multilingual model training where there is more than one language ID per sample

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

# Changelog 
- [audio_to_text.py] modified to parse the manifest in the new format
- [collections.py] modified to not require global lang id per sample in this case (since lang id will be specified on each text span)

# Usage
Use manifest format as shown below. No other code changes required.

```json
{"audio_filepath": "_data_cs_constructed_data_v1_0.wav", "shard_id": 168, "duration": 17.715125, "text": [{"lang": "es", "str": "es probablemente la amiga de puck que m\u00e1s aparece y m\u00e1s presencia tiene "}, {"lang": "en", "str": "she might have gone on but that she caught kinraid's eyes looking at her with kindly admiration "}, {"lang": "es", "str": "o las que tienes de estar con alguien que no lo es porque"}]}
```

# 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**:
- [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)
