Register LSIF upload endpoint in internal frontend
Created by: efritz
The auto-indexer accesses the frontend via SRC_FRONTEND_INTERNAL, but that API does not have the lsif/upload endpoint registered.
Instead of adding a new envvar to access the public port (which would also require generating a sudo access token for the app to use), we register the codeintel upload endpoint in the internal API in a way that can bypass the upload auth mechanism.
This renames a package {httpapi}->{enterprise}, which contains a hook for the enterprise code to update the code intel upload handler. There are some other globals in the frontend package which I think should be consolidated here over time (such as campaign resolvers cc @mrnugget ).