OutputPage: Support UploadPath in testTransformResourcePath()

OutputPage: Support UploadPath in testTransformResourcePath()

Updated tests to reflect this use case. Currently we assume all web-accessible
paths within ResourceBasePath (e.g "/w") to exist on disk at the same path
in $IP (e.g. "/var/www/mw").

While in theory any number of web server rewrites or aliases could exist,
there is one case in particular that we should support since the information
is available in the configuration: UploadDir and UploadPath. This path may
be rewritten in a way that varies by wiki in multi-wiki installs that share
the same source code. E.g. a server may rewrite "/w/images" to somewhere
else, which means it will not match the directory on disk that is shared
between wikis.

Bug: T155146
Change-Id: I320478c9c262cc012f08b585b48d290594ec2420