R1:69d12f64baf9

Add repositories to Diviner

Summary: Fixes T8352. Associate Diviner books and atoms with a repository. This relationship is not really surfaced anywhere in the UI but provides metadata that contextualises search results. Depends on D13091.

Test Plan: Ran `diviner generate --repository ARC` and then went to `/diviner/book/arcanist/`.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T7703, T8352

Differential Revision…