Allow use as library in addition to command line

[rhubarb]

Excellent tool - I'm currently using it as a library in my own CLI, but there are some issues:

1. I have to set where and where_document to None deliberately when calling chroma_export, because their default values are options, not None - leading to JSON parsing errors.

2. I can only export to a file or stdout, it would be nice to get the list of docs returned

3. The collection metadata is not preserved - perhaps an optional line at the top of the jsonl output.

[tazarov]

@rhubarb, thank you for the feedback. I'll get right on it.

[tazarov]

@rhubarb, I think the latest main addresses your issue. I'll cut a release tomorrow.

you can now use chroma_import as a regular function in your code, and there is chroma_import_cli, which is the CLI-specific function for typer.