This commit adds the xDS resources needed for INBOUND traffic from peer
clusters:
- 1 filter chain for all inbound peering requests.
- 1 cluster for all inbound peering requests.
- 1 endpoint per voting server with the gRPC TLS port configured.
There is one filter chain and cluster because unlike with WAN
federation, peer clusters will not attempt to dial individual servers.
Peer clusters will only dial the local mesh gateway addresses.
