message: add socket.handle
diff: @@ -321,6 +321,11 @@ namespace bee::lua_socket {
  }
  return 0;
  }
  + static int handle(lua_State* L) {
  + luafd& self = checkfd(L, 1);
  + lua_pushlightuserdata(L, (void*)(intptr_t)self.fd);
  + return 1;
  + }
  static luafd& pushfd(lua_State* L, socket::fd_t fd, socket::protocol protocol, luafd::tag type) {
  luafd* self = (luafd*)lua_newuserdatauv(L, sizeof(luafd), 0);
  new (self) luafd(fd, protocol, type);
  @@ -335,6 +340,7 @@ namespace bee::lua_socket {
  {"shutdown", shutdown},
  {"status", status},
  {"info", info},
  + {"handle", handle},
  {"__tostring", tostring},
  {"__close", toclose},
  {"__gc", gc},
  