tests: run tst_qmediaplayerbackend with Windows backend on CI

The Windows MediaEngine backend is already enabled on CI, but
tst_qmediaplayerbackend skips itself entirely there, because the VMs
used to have no audio device. They emulate one now, so remove that skip.

Media Foundation opens Ogg and Matroska files only if optional Windows
media extensions are installed, which is not the case on CI. Skip
testMediaFilesAreSupported on WMF, like on Darwin, and skip the
durationDetectionIssues rows whose file can't be loaded.

On Windows 10, IMFMediaEngine::Shutdown() hangs after loading
h264_avc1_yuv420p10le_tv_bt2020.mov, so don't select that file there
for now.

Change-Id: Ib050af7f0b326c98d8c519be5364f5ac6ca5dd0f
Reviewed-by: Tim Blechmann <tim.blechmann@qt.io>