Containerize Go-GTP pseudo ENB

[Taylor Carpenter]

Containerize the Go-GTP pseudo ENB

Related to containerizing P-GW (#313) and S-GW (#314)

Prereq:

• verify host-based version in #312
• code available in https://github.com/vulk/go-gtp/tree/master/examples/gw-tester/enb
• Packet access

Tasks:

• Create Dockerfile which uses pseudo ENB from https://github.com/vulk/go-gtp/tree/master/examples/gw-tester/enb
• Create readiness and livelyness tests
• ENB ports are exposed (external to the Pod)
• Create a branch on https://github.com/vulk/go-gtp if code changes are needed
• Create new go-gtp example folder in fork if it makes sense for containerized updates (that make the host based no longer work as expected)
• Create pull request for any changes to https://github.com/wmnsk/go-gtp/, if it makes sense

Testing:

• Deploy K8s cluster to Packet
• Deploy containerized ENB to Packet using kubectl
• Verify container and pod starts
• Verify ENB ports are exposed

[Taylor Carpenter]

Added to https://github.com/cncf/cnf-testbed/tree/e65b603085e0a6f6fc2d8ffe0711493ac4356e15/examples/network_functions/go-gtp