codeintel: Repo-independent upload and index pages

Created by: efritz

This covers https://github.com/sourcegraph/sourcegraph/issues/10837 and https://github.com/sourcegraph/sourcegraph/issues/10835.

Site-admins should be able to see LSIF uploads and auto-index behavior without having to look at a particular repository. This is especially true for auto-indexing as we currently don't have a way to determine what is being indexed without (1) blindly looking at repository settings pages, or (2) having direct access to postgres and some knowledge about the auto-indexing heuristic (which will be rapidly changing).

This simply makes the code intelligence repo settings pages available from the site-admin page and drops the repository filter from the queries.

Additional UX improvements will be done in https://github.com/sourcegraph/sourcegraph/pull/11320