When manila API is served behind a proxy, the
"script_name" in the request can have the proxy
component in it. So, this patch fixes the version
selection logic by looking for the version in the
script name string instead of equivalence.
In addition, this patch adds some missing unit
tests and fixes tests that invoke a mocked
wsgi app for testing request context.
Change-Id: I0363d7174f3d7ddefa8ced59b182faed665e9c36
Partial-Bug: #1815038
Closes-Bug: #1818081
0d8310ec7a