tst_qmediacapturesession: Add test setting QImageCapture resolution

Setting QImageCapture resolution should aim to have the resolution be
propagated to the video source, so scaling won't be applied.

Add test calling QImageCapture::setResolution with a resolution provided
by QCameraDevice::photoResolutions, and ensure the available QVideoFrame
has the correct resolution.

Pick-to: 6.12
Change-Id: I528e7ccfb47de1b5a2b3c017b5522a1e3f0ad3a6
Reviewed-by: Nils Petter Skålerud <nils.petter.skalerud@qt.io>
Reviewed-by: Artem Dyomin <artem.dyomin@qt.io>