Add `bulk embed` command.

[koaning]

It should be possible, with embetter as an optional dependency, to add a bulk embed command to this project. Maybe use it like:

# For text
python -m bulk embed text file-in.jsonl file-out.jsonl --pipeline sentence-tfm --model LaBSE

# For images
python -m bulk embed image file-in.jsonl file-out.jsonl --pipeline timm --model VGG16

Things to think about:

• how to keep the default pipelines lightweight
• maybe also allow functions to be imported from a notebook
• think about progress bars, maybe with rich

[koaning]

Closing this issue. The future of this project is Jupyter Widgets.