test: Move test objects to libtest

Create a subdirectory to contain the libtest helper library.

Define two variables to clarify when tests are aimed at public or
internal components.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

test/libtest/test.cpp

@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2018, Google Inc.
+ *
+ * test.cpp - libcamera test base class
+ */
+
+#include "test.h"
+
+Test::Test()
+{
+}
+
+Test::~Test()
+{
+}
+
+int Test::execute()
+{
+	int ret;
+
+	ret = init();
+	if (ret < 0)
+		return ret;
+
+	ret = run();
+
+	cleanup();
+
+	return ret;
+}