We don't want to depend on the entire site configuration when we only
need a few specific settings.
This change additionally means that these services no longer see a live
version of the settings, but rather a copy. This means in tests you
really do have to call overrideMwServices() if you want services to pick
up your config changes.
ResourceLoader and SearchEngineConfig will need more work to port,
because they expose their member Config in a getter, and the getter is
actually used.
Parser and NamespaceInfo are also relatively complicated, so I split
them into separate patches.
Tested with 100% code coverage. \o/
Depends-On: If6534b18f6657ec1aba7327463f2661037f995b3
Change-Id: I1a3f358e8659b49de4502dc8216ecb6f35f4e02a
18ec468633