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

tlssock.go

@@ -9,6 +9,7 @@
 package net
 
 import (
+	"context"
 	"internal/itoa"
 	"io"
 	"net/netip"
@@ -139,3 +140,10 @@ func (c *TLSConn) Handshake() error {
 	panic("TLSConn.Handshake() not implemented")
 	return nil
 }
+
+// HandshakeContext runs the client or server handshake protocol if it has not
+// yet been run. TINYGO: TLS is offloaded to the network device; this exists to
+// satisfy callers (e.g. pion/ice) that require the context-aware variant.
+func (c *TLSConn) HandshakeContext(ctx context.Context) error {
+	return c.Handshake()
+}