addons: addressvirtual: enslave macvlans on vrf slaves to the vrf master

addons: addressvirtual: enslave macvlans on vrf slaves to the vrf master

Ticket: CM-11803
Reviewed By: dsa, scotte, wkok, nikhil, julien
Testing Done: tested config of address-virtual lines on vrf slaves

This patch does the following:
- addressvirtual: enslaves macvlans created on vrf slaves
to the vrf master
- vrf: when looking for stale slaves on vrf master, skip
macvlan devices. This code does basic checking right now
and can be improved to include more cases.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>