Make sure the global session data in $wgRequest is used for doApiRequest
per default, and return it's content among with the request's results.
Previously, an empty session was used per default, and the local context's
session data would get out of sync with $wgRequest.
This change allows for the following assumptions to hold in test cases:
* within the same function, changes to the session made by one api call
will be visible to subsequent api calls.
* the session data returned by doApiRequest is the actual status of the
session as manipulated by the api call. This session data can be passed
to subsequent api calls.
Note that the session data is still reset for every call to a test
function.
Change-Id: Ia20cf0ccfcdca736dd5da3444b14fbdd1c5def46
62ac6f3722