libcamera: camera: Add Camera properties

Add a method to the Camera class to retrieve the Camera properties
registered by the pipeline handler.

While at it, reword the Camera::controls() operation documentation to
specify that the camera control information are constant during the
camera lifetime not their value, while the camera properties value are
the actually static information.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

include/libcamera/camera.h

@@ -86,6 +86,7 @@ public:
 	int release();
 
 	const ControlInfoMap &controls();
+	const ControlList &properties();
 
 	const std::set<Stream *> &streams() const;
 	std::unique_ptr<CameraConfiguration> generateConfiguration(const StreamRoles &roles);