codeintel: streamline LSIF dependency autoindexing

Created by: Strum355

Previously, uploading an LSIF index would create new repositories based on references in the upload, such as those in maven artifact hosts like maven central. However, these would not get auto-indexed if they were seen for the first time by Sourcegraph, as the repositories are created async and not in time for them to be referenceable by the rest of the indexing pipeline.

This PR changes this by using the requeueing capabilities to wait for the relevant external service(s) (if any) to have synced and for the repositories to have been cloned before queueing an auto-index record for the referenced repositories.