geneve gtpu vxlan vxlan-gpe: VRF-aware bypass node

geneve gtpu vxlan vxlan-gpe: VRF-aware bypass node

Bypass node MUST NOT intercept a packet if destination IP doesn’t match
a local address.  However IP address interpretation depends on the VRF,
hence bypass node must take that into account.

This patch also factors-out common VTEP management and checking code.

Type: improvement
Signed-off-by: Nick Zavaritsky <[email protected]>
Change-Id: I5665d94882bbf45d15f8da140c7ada528ec7fa94