AutoNAT v2

[thomaseizinger]

Preliminary tracking issue around all the work that needs to happen around AutoNATv2 or issues that are associated with it.

### Implementation tasks
- [ ] https://github.com/libp2p/rust-libp2p/issues/4226

### Follow-up work
- [ ] https://github.com/libp2p/rust-libp2p/issues/3953

### Known bugs
- [ ] https://github.com/libp2p/rust-libp2p/issues/3986
- [ ] https://github.com/libp2p/rust-libp2p/issues/3889
- [ ] https://github.com/libp2p/rust-libp2p/issues/3308
- [ ] https://github.com/libp2p/rust-libp2p/issues/4873
- [ ] https://github.com/libp2p/rust-libp2p/issues/5059

[umgefahren]

Since this is my grant work, could you please assign me?

[mxinden]

For others to follow along, grant proposal: filecoin-project/devgrants#1421