dep: Add catch2 unit test framework and wire it up

To enable the test suite, make sure to configure CMake with -DBUILD_TESTING=1 , since it is disabled by default. The catch2 dependency will be downloaded during configure time.

Also add a new target "tests-common", which includes unit tests for the "common" project. To finally run the tests use the "test" target.

CircleCI: Run unit tests
(cherry picked from commit 6a28ee7b2a4269aa7e43265d1cd0067537e3e883)

tests/common/test-main.cpp

@@ -0,0 +1,20 @@
+/*
+ * This file is part of the TrinityCore Project. See AUTHORS file for Copyright information
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This program 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 General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#define CATCH_CONFIG_MAIN
+#include "catch2/catch.hpp"