Add diagrams to NAT Traversal tests #388

Specification

The NAT traversal tests are complex and rely on many utility functions, making it difficult to know what is happening in these tests. It would be helpful to have diagrams at the top of each test showing the architecture of the namespaces and agents involved in each test.

Diagrams needed:

• DMZ
  • Agent 1 (DMZ) -> Agent 2 (DMZ)
  • Agent 1 (DMZ) -> Seed Node -> Agent 2 (DMZ)
• Endpoint-independent mapping (EIM)
  • Agent 1 (EIM) -> Agent 2 (DMZ)
  • Agent 1 (DMZ) -> Agent 2 (EIM)
  • Agent 1 (EIM) -> Agent 2 (EIM)
  • Agent 1 (EIM) -> Seed Node -> Agent 2 (EIM)
  • Agent 1 (EIM) -> Seed Node -> Agent 2 (EDM)
• Endpoint-dependent mapping (EDM)
  • Agent 1 (EDM) -> Agent 2 (DMZ)
  • Agent 1 (DMZ) -> Agent 2 (EDM)
  • Agent 1 (EDM) -> Seed Node -> Agent 2 (EDM)
  • Agent 1 (EDM) -> Seed Node -> Agent 2 (EIM)

Additional context

• First suggested here: Tests for NAT-Traversal and Hole-Punching #381 (comment)

Tasks

1. Create diagrams for each of the NAT tests using ASCII flow
2. Modify test descriptions where necessary to make them clearer