test: Add a new suite for commands

Add a new suite for 'cmd' tests, used for testing commands. These are
kept in the test/cmd directory.

For now it is empty, but it will be used for coreboot-command tests.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/test/cmd.h

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2023 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#ifndef __TEST_CMD_H__
+#define __TEST_CMD_H__
+
+#include <test/test.h>
+
+/* Declare a new command test */
+#define CMD_TEST(_name, _flags) UNIT_TEST(_name, _flags, cmd_test)
+
+#endif /* __TEST_CMD_H__ */