Add another bgp group on MX if EBGP peers are present

Currently, device manager only programs one BGP group on MX of type internal. But if it has EBPG peers, we need another group of type external. We should add neighbors in appropriate group.

Change-Id: I26c6b41f9ca6f3161a1f88a8d57895fd9f8ed13b
Closes-Bug: 1395940
Merge "Add another bgp group on MX if EBGP peers are present"