zebra: advertise svi ip as macip route changes

zebra: advertise svi ip as macip route changes

In Asymmetric and symetric routing scenario in EVPN
where each VTEP pair having different set of addresses
for the SVIs.
This knob allows reachability (ping connectivity) of
SVI IPs and resolve ARP resoultion VTEPs across racks.

This knob should not be used when same SVI IPs configured
on VTEPs across racks or when advertise default gateway
is configured.

Ticket:CM-23782
Testing Done:
Bring up EVPN symmetric routing topology with different
SVI IPs on different VTEPs. Enable advertise svi ip
at each VTEP, remote VTEPs installs arp entry for
SVI IPs via EVPN type-2 route exchange.

Signed-off-by: Chirag Shah <chirag@cumulusnetworks.com>