T4825: Add interface type veth

Add interface type veth (Virtual ethernet)
One of the usecases it's interconnect different vrf's and
default vrf via bridge

set interfaces virtual-ethernet veth0 peer-name 'veth1010'
set interfaces virtual-ethernet veth1010 address '10.0.0.10/24'
set interfaces virtual-ethernet veth1010 peer-name 'veth0'
set interfaces virtual-ethernet veth1010 vrf 'foo'
set interfaces bridge br0 address '10.0.0.1/24'
set interfaces bridge br0 member interface veth0