Add array controls support to the ControlValue class. The polymorphic class can now store more than a single element and supports access and creation through the use of Span<>. Signed-off-by: Jacopo Mondi <jacopo@jmondi.org> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>