test(dbus): Add unit tests for PiControl D-Bus interface

Introduces initial tests for the PiControl interface in
`dbus_middleware1`. These tests cover basic functionality like checking
activity status and resetting the driver while verifying IOCTL calls.

tests/dbus_middleware1/process_image/__init__.py

@@ -0,0 +1,3 @@
+# -*- coding: utf-8 -*-
+# SPDX-FileCopyrightText: 2025 KUNBUS GmbH
+# SPDX-License-Identifier: GPL-2.0-or-later