feat(unittests): add a unit test framework.

This patch adds all the infrastructure needed to run unit tests for
RMM, including a new variant for platform host, called `host_test`.

To build and run the tests:

cmake -DRMM_CONFIG=host_defcfg -DHOST_VARIANT=host_test \
  -DCMAKE_BUILD_TYPE=Debug -S ${RMM_SOURCE_DIR} -B ${RMM_BUILD_DIR}
cmake --build ${RMM_BUILD_DIR} -- run-unittests

Signed-off-by: Javier Almansa Sobrino <javier.almansasobrino@arm.com>
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
Change-Id: If16686e111d91c563f8e7281d4ee7ca2864125ae
diff --git a/plat/host/host_test/src/test_main.cpp b/plat/host/host_test/src/test_main.cpp
new file mode 100644
index 0000000..a1c57e8
--- /dev/null
+++ b/plat/host/host_test/src/test_main.cpp
@@ -0,0 +1,13 @@
+/*
+ * SPDX-License-Identifier: BSD-3-Clause
+ * SPDX-FileCopyrightText: Copyright TF-RMM Contributors.
+ */
+
+#include <CppUTest/CommandLineTestRunner.h>
+#include <CppUTest/TestHarness.h>
+#include <test_groups.h>
+
+int main (int argc, char** argv)
+{
+        return CommandLineTestRunner::RunAllTests(argc, argv);
+}