tunneling: get skb marking to work properly with tunnels

tunneling: get skb marking to work properly with tunnels

There are two issues that this patch fixes:
1. it was impossible to set skb mark at all through
   NXM_NX_PKT_MARK register for tunnel packets; AND
2. ipsec_xxx tunnels would not be marked with the default
   IPsec mark (broken by d23df9a87 "lib/odp: Use masked set
   actions.").

This patch also adds anti-regression tests to prevent such
breakages in the future.

Signed-off-by: Ansis Atteka <aatteka@ovn.org>
VMware-BZ: #1653178
Acked-by: Jarno Rajahalme <jarno@ovn.org>