tests: add optional GoogleTest-based smoke-tests and CMake support (BUILD_GTEST_SMOKE)

Lts/DDS/DdsUnitTestsPlaceholder/ddsFunctionTopicTests_gtest.cpp

@@ -0,0 +1,9 @@
+#include <gtest/gtest.h>
+#include <map>
+
+TEST(FunctionTopicSmokeGTest, Containers) {
+  std::map<std::string,int> m;
+  m["one"] = 1;
+  m["two"] = 2;
+  EXPECT_EQ(m["two"], 2);
+}