[Meta] Improving libp2p discoverability and connectivity

[jacobheun]

This is a Meta issue for tracking several sub systems involved in improving discoverability and connectivity in js-libp2p. This list is not an exhaustive and will evolve over time.

Connectivity

• [ ] AutoRelay support
• [ ] AutoNAT to determine dialability

Discoverability

• [ ] Connect to closest peers
• [ ] Implement the DHT changes from go-ipfs 0.5 to improve performance
• [ ] Implement the rendezvous protocol
• [X] Delegate routing