LSIF: Unify lsif dump and upload entities

Created by: efritz

https://github.com/sourcegraph/sourcegraph/pull/7486 merged the lsif dump and uploads table together, making only one table (uploads) and a view into the ones that have been processed (dumps). This is part of an ongoing effort to merge two concepts into one and remove some of the debt from having a non-postgres job queue.

Backend: This PR removes all dump endpoints from the lsif-server and all dump resolvers from the GraphQL API and moves any dump-only features into the uploads endpoints/resolvers.

Web: Remove the list of uploads from site-admin. Retain the /site-admin/lsif-upload page (although it is not navigable from the sidebar). Simplify the data on the code intelligence page in the repository settings. Move the lsif-upload page (unchanged) into repo settings, and replace the original site admin page with a redirect. This keeps backcompat with src-cli, which may not be much of an issue after https://github.com/sourcegraph/sourcegraph/pull/7600.