tc/pedit: Extend pedit to specify offset relative to mac/transport headers

tc/pedit: Extend pedit to specify offset relative to mac/transport headers

Utilize the extended pedit netlink to set an offset relative to a
specific header type. Old netlink only enabled the user to set
approximated  offset relative to the IPv4 header.

To use this extended functionality need to use the 'ex' keyword after
'pedit' and before any 'munge'.
e.g:
$ tc filter add dev ens9 protocol ip parent ffff: \
    flower \
      ip_proto udp \
      dst_port 80 \
    action pedit ex munge \
      ip dst set 1.1.1.1 \
      pipe \
    action mirred egress redirect dev veth0

Signed-off-by: Amir Vadai <amir@vadai.me>