libcamera: camera_sensor: Add tryFormat()

Add a function to the CameraSensor class that allows to test a format
without applying it to the subdevice and without modifying any control
value associated with the camera sensor.

Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

include/libcamera/internal/camera_sensor.h

@@ -56,6 +56,7 @@ public:
 				      const Size &size) const;
 	int setFormat(V4L2SubdeviceFormat *format,
 		      Transform transform = Transform::Identity);
+	int tryFormat(V4L2SubdeviceFormat *format) const;
 
 	const ControlInfoMap &controls() const;
 	ControlList getControls(const std::vector<uint32_t> &ids);