Camera fails to start in CaptureStillImage mode if a capture resolution is specified.

The example below with the gstreamer camerabin backend will (probably, depending on the camera) fail to display the viewfinder unless either the captureMode or resolution binding is removed.

VideoOutput {
    source: Camera {
        captureMode: Camera.CaptureStillImage
        imageCapture.resolution: "1280x720"
    }
}

This happens when the hardcoded viewfinder dimensions in the camerabinsession.cpp aren't supported by the camera, and can be avoided somewhat by selecting a resolution from the camera's list of supported resolutions.