Allow the user to specify the viewfinder resolution instead of guessing

Guessing badly prevents the camerabin pipeline from loading at all and
the fallbacks used are not representive of the capabilities of most
cameras. So either stay out of the process and let gstreamer negotiate
a resolution if it can, or use a resolution supplied through the viewfinder
settings control by someone hopefully better informed.

Task-number: QTBUG-30842
Change-Id: Iec2dcc2476f38822f9e0d02301e46a1f49b7c6da
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>

src/plugins/gstreamer/camerabin/camerabinservice.cpp

@@ -61,6 +61,7 @@
 #include "camerabinimageprocessing.h"
 #include "camerabincapturebufferformat.h"
 #include "camerabincapturedestination.h"
+#include "camerabinviewfindersettings.h"
 #include <private/qgstreamerbushelper_p.h>
 
 #include <private/qgstreameraudioinputselector_p.h>
@@ -240,6 +241,9 @@ QMediaControl *CameraBinService::requestControl(const char *name)
     if (qstrcmp(name, QCameraCaptureBufferFormatControl_iid) == 0)
         return m_captureSession->captureBufferFormatControl();
 
+    if (qstrcmp(name, QCameraViewfinderSettingsControl_iid) == 0)
+        return m_captureSession->viewfinderSettingsControl();
+
     return 0;
 }