selftests: forwarding: Add test cases for flower port range matching

Add test cases to verify that flower port range matching works
correctly. Test both source and destination port ranges, with different
combinations of IPv4/IPv6 and TCP/UDP, on both ingress and egress.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Link: https://lore.kernel.org/r/9d47c9cd4522b2d335b13ce8f6c9b33199298cee.1689092769.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>