With a separate service for each of the NameTableStore tables, it
wasn't possible to instantiate a NameTableStore for a foreign wiki,
leading to the inelegant situation of having RevisionStoreFactory
construct a new NameTableStoreFactory every time a RevisionStore for a
foreign wiki was requested. These NameTableStore objects were not
tracked in any structured way, so there was no way to reset them for
So, introduce NameTableStoreFactory, which tracks object instances for
both local and remote table access.
This also avoids having schema details in ServiceWiring.php.