net/sfc: add facilities to handle bundles of actions

net/sfc: add facilities to handle bundles of actions

There are MAE actions which do not have uniform counterparts
in terms of RTE flow. However, there are bundles of RTE flow
actions which can be considered as such counterparts.

Implement facilities to handle related RTE flow actions as
parts of a whole. These facilities will be used by a later
patch to add support for VLAN PUSH actions bundle.

Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
Reviewed-by: Andy Moreton <amoreton@xilinx.com>