Extend the cam tool to allow configuring more than one stream. Add an optional parameter to the --stream option to specify a usage role for the stream. The stream role is passed to libcamera to give it control over which streams to use. To support multiple streams, creation of requests needs to be reworked to limit the number of requests to match the stream with the least number of buffers. This should be improved in the future as the tool and the library evolve. Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>