Add Nemotron VLM support in video captioning

[ronjer30]

Description

Adds support for the Nemotron Nano 12B V2 VLM

Usage

1. Download model checkpoints
2. Run

python tutorials/video/getting-started/video_split_clip_example.py \
  --video-dir </path/to/videos_directory/> \
  --output-clip-path ./outputs \
  --generate-captions \
  --captioning-algorithm nemotron \
  --nemotronh-vl-model-path </path/to/checkpoints/> \
  --captioning-batch-size 8 \
  --no-generate-embeddings 

Checklist

• I am familiar with the Contributing Guide.
• New or Existing tests cover these changes.
• The documentation is up to date with these changes.

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[ronjer30]

Thanks @suiyoubi, I've addressed the issues, added tests and updated existing ones as well.