Fix I2CServer.send_message/1 with SimpleI2CDevice

This commit fixes the issue where the `I2CServer.send_message/1`
function only worked with `I2CDevice` devices and not with
`SimpleI2CDevice` devices.

The problem was that the handling of the `:send_message` was not being
specialized for `SimpleI2CDevice` devices.

Author: bithium

lib/circuits_sim/i2c/i2c_server.ex

@@ -126,7 +126,7 @@ defmodule CircuitsSim.I2C.I2CServer do
   end
 
   def handle_call({:send_message, message}, _from, state) do
-    {result, new_device} = I2CDevice.handle_message(state.device, message)
+    {result, new_device} = do_send_message(state, message)
     {:reply, result, %{state | device: new_device}}
   end
 
@@ -165,6 +165,14 @@ defmodule CircuitsSim.I2C.I2CServer do
     SimpleI2CDevice.render(state.device)
   end
 
+  defp do_send_message(%{protocol: I2CDevice} = state, message) do
+    I2CDevice.handle_message(state.device, message)
+  end
+
+  defp do_send_message(%{protocol: SimpleI2CDevice} = state, message) do
+    SimpleI2CDevice.handle_message(state.device, message)
+  end
+
   defp simple_read(state, 0, acc) do
     result = acc |> Enum.reverse() |> :binary.list_to_bin()
     {result, state}