Milestone summary: GoEPC Milestone 1: Build a K8s-based GoEPC user plane using a segmented+routed network

Summary of https://github.com/cncf/cnf-testbed/milestone/56

Value:
- Meetings customer requirements (network security policies)
- Cloud native principles: declarative apis and config, observability
- K8s-native

Initial Goal: Send traffic through separated isolated and routed networks in the EPC user plane

Requirements:
- Must support using separate routed networks (eg. usually multiple interfaces) for EPC services
- Must support 3GPP standards for S-GW and P-GW including GTP tunnels
- Must use declarative K8s native configuration
- Minimize out-band, non-K8s, no custom vendor stuff if possible
- Should re-use existing EPC software for the services (eg. OpenAirInterface, OMEC, go-gtp) rather than writing them from scratch
- Go-gtp chosen
- Must run on Kubernetes

Phases:

- [x] POC go-gtp, host-only version running on Packet https://github.com/cncf/cnf-testbed/issues/323 and https://github.com/cncf/cnf-testbed/issues/312
- [x] POC Docker version running on Packet https://github.com/cncf/cnf-testbed/issues/328 and https://github.com/cncf/cnf-testbed/issues/324
- [ ] POC single-node bridged network version running on K8s with Helm charts for CNFs https://github.com/cncf/cnf-testbed/issues/327
- [ ] - POC multi-node bridged network version https://github.com/cncf/cnf-testbed/issues/330
- [ ] - POC routed network version https://github.com/cncf/cnf-testbed/issues/331

Diagram: