net: SyscallConn, Dialer.Control and IPConn.Read are missing for grpc and wazero #95

Compiling grpc and wazero under TinyGo fails on three missing pieces.

TCPListener has no SyscallConn, which wazero's socket layer requires. Dialer has no Control or ControlContext field, which grpc sets. IPConn has no Read, so it does not satisfy io.Reader, which grpc type switches on.

All three can be source compatibility fills, since the netdev dial exposes no raw syscall.RawConn to hand out. PR #78 adds them.