* feat(wip): hysteria realms
* feat: port prediction for punching symmetric NAT
* feat: add "cert" subcommand for easy self signed cert generation
* refactor: update address scheme from "hysteria2+realm" to just "realm"
* fix: give up on realm register fatal errors
* chore: update formatting (gofumpt)
* perf: realm proxy UDP methods on PunchPacketConn so quic-go and obfs keep DF/PMTU and buffer sizing
* feat: add support for local UDP source port config in realm addresses
* doc: README for realm pkg