net: add UDP listen, resolver, DNSError, and TCP listener APIs for wasm (#63)

* net: add UDP listen, resolver, DNSError, and TCP listener APIs for wasm

TinyGo's net package was missing several symbols that upstream Go's
js/wasm net declares, blocking builds that pull pion/transport, pion/dtls,
and similar (via netbird's WASM client). Add them, backed by the existing
netdev abstraction so they compile for all targets and no-op cleanly under
nopNetdev (matching Go's js runtime behavior):

- DNSError type (dnserror.go), copied from Go 1.26.2.
- Resolver + DefaultResolver with LookupHost/LookupIP/LookupIPAddr/
  LookupNetIP/LookupPort; LookupHost/LookupIP package funcs; Dialer.Resolver
  field for API compatibility.
- UDPConn: ListenUDP, ReadFromUDP(AddrPort), WriteToUDP(AddrPort),
  SetReadBuffer, SetWriteBuffer.
- TCPConn: CloseRead, SetNoDelay, SetReadBuffer, SetWriteBuffer,
  ReadFrom(io.Reader).
- TCPListener: ListenTCP, AcceptTCP, SetDeadline; ListenPacket package func.
- Interface: Addrs, MulticastAddrs stubs.

* more complete PR for adding more net support (#64)

* format unixsock

http/server.go

@@ -2779,6 +2779,23 @@ type Server struct {
 	// value.
 	ConnContext func(ctx context.Context, c net.Conn) context.Context
 
+	// TLSNextProto optionally specifies a function to take over
+	// ownership of the provided TLS connection when an ALPN
+	// protocol upgrade has occurred. The map key is the protocol
+	// name negotiated. The Handler argument should be used to
+	// handle HTTP requests and will initialize the Request's TLS
+	// and RemoteAddr if not already set. The connection is
+	// automatically closed when the function returns.
+	// If TLSNextProto is not nil, HTTP/2 support is not enabled
+	// automatically.
+	TLSNextProto map[string]func(*Server, *tls.Conn, Handler)
+
+	// HTTP2 configures HTTP/2 connections.
+	//
+	// This field does not yet have any effect.
+	// See https://go.dev/issue/67813.
+	HTTP2 *HTTP2Config
+
 	inShutdown atomicBool // true when server is in shutdown
 
 	disableKeepAlives int32     // accessed atomically.