In preparation for support to set the value of a YamlObject, rename the Getter structure to Accessor. The structure will be extended with a set() function. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com> Reviewed-by: Isaac Scott <isaac.scott@ideasonboard.com>