Addon Manager: Add unit test framework

Adds the framework for unit testing, and a few tests of the utilities functions.

src/Mod/AddonManager/AddonManagerTest/gui/test_gui.py

@@ -0,0 +1,33 @@
+# -*- coding: utf-8 -*-
+
+# ***************************************************************************
+# *   Copyright (c) 2022 FreeCAD Project Association                        *
+# *                                                                         *
+# *   This file is part of the FreeCAD CAx development system.              *
+# *                                                                         *
+# *   This library is free software; you can redistribute it and/or         *
+# *   modify it under the terms of the GNU Lesser General Public            *
+# *   License as published by the Free Software Foundation; either          *
+# *   version 2.1 of the License, or (at your option) any later version.    *
+# *                                                                         *
+# *   This library is distributed in the hope that it will be useful,       *
+# *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+# *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU     *
+# *   Lesser General Public License for more details.                       *
+# *                                                                         *
+# *   You should have received a copy of the GNU Lesser General Public      *
+# *   License along with this library; if not, write to the Free Software   *
+# *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA         *
+# *   02110-1301  USA                                                       *
+# *                                                                         *
+# ***************************************************************************
+
+import unittest
+import FreeCAD
+
+class TestGui(unittest.TestCase):
+
+    MODULE = 'test_gui' # file name without extension
+
+    def setUp(self):
+        pass