prototype cellxgene schema CLI changes needed to validate fragments

[Bento007]

An experimental validator is required to validate 10x ATAC-SEQ data and generate fragment index files. This is to keep the data science team unblocked.

DoD:

• Produce a prototype of the cellxgene-schema cli that can validate 10x ATAC-SEQ and generate Index file for the fragment files.
• The prototype can be installed by data scientist for exprimenting.
• Issues created with work outline the steps needed to productionalize the prototype.

Dependencies

• Define the schema requirements for 10x multiome
• Explorer alternative storage formats for 10x ATAC_SEQ
• Generate TBI from anndata and fragment files using Tabix

[Bento007]

Experimental notebook: https://gist.github.com/Bento007/a52171c352e15a7bca320d7b025374b4

[Bento007]

The work remaining to productionalize the prototype includes:

• add unit tests and test coverage
• integrate into the ingestion workflow
• run a memory profile of the new command.