feat(chat): simplify socket response

Add helper methods to create the tuples `{:ok, socket}` and
`{:noreply, socket}`, and make them available in `SlaxWeb` module.

lib/slax_web/live/socket_helpers.ex

@@ -0,0 +1,9 @@
+defmodule SlaxWeb.SocketHelpers do
+  @moduledoc """
+  Helper functions to encapsulate a socket into proper tuples.
+  """
+
+  def ok(socket), do: {:ok, socket}
+
+  def noreply(socket), do: {:noreply, socket}
+end