Add support to ControlId for querying direction information. This allows applications to query whether a ControlId is meant for being set in controls or to be returned in metadata or both. This also has a side effect of properly encoding this information, as previously it was only mentioned losely and inconsistently in the control id definition. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>