resourceloader: Remove use of msg_resource_links table
This table is not needed because module names and their messages
array are available to the runtime environment at very little cost.
The only purpose it was serving is reverse lookup from message
key to module name (e.g. when MessageCache receives update that
need to propagate to MessageBlobStore). However that is better
achieved by simply looping through modules in PHP. The overhead
of a database is not worth this minor convenience.
- insertMessageBlob: Doesn't need to update msg_resource_links.
- updateModule: Doesn't need to update msg_resource_links.
- getUpdatesForMessage: Reimplement with list from memory instead of msg_resource_links.
The database table will be removed in If009e2620e59002e1.