codeintel: RFC 235: Migrate SQLite data to Postgres
Created by: efritz
A step towards RFC 235: Move LSIF data to Postgres. Closes https://github.com/sourcegraph/sourcegraph/issues/13888.
This PR migrates existing data to the Postgres-backed bundle store introduced https://github.com/sourcegraph/sourcegraph/pull/13923. Do not merge this PR until https://github.com/sourcegraph/sourcegraph/pull/13924 has been completed and deployed.