InfraBGPSession references InfraBGPPeerGroup via peer_group HFID,
so peer groups must be committed before sessions are created.
Split 09-bgp.yml into:
- 09-bgp.yml: InfraBGPRouterConfig + InfraBGPPeerGroup
- 10-bgp-sessions.yml: InfraBGPSession + InfraBGPAddressFamily
Renamed: 10-vrfs→11, 11-mlag→12. Now 12 object files total.