outsource using go-libp2p

[systemshift]

According to the contributing file, it is recommended to vendor everything when possible.
libp2p has a go implementation which seem to be a good candidate to use https://github.com/libp2p/go-libp2p

It might make it easier to implement DHT using it, but it isn't clear how safe implementing it exclusively with i2p would work out, it might be also worthy to note the maintainer includes tor & i2p as part of their roadmap. So further research is needed.

[majestrate]

i2p's bittorrent dht is really weird and has nonstardard isms like requiring use of both repliable and non-repliable i2p datagrams (it is still normal kad). dropping in libp2p's dht probably won't work with i2psnark and friends. it may work with lokinet support as it's a blank slate and we can do whatever we want with it.