Vendor rlottie sources with CMake and MinGW build adjustments

tools/chatgui/rlottie_src/test/testsuite.cpp

@@ -0,0 +1,6 @@
+#include <gtest/gtest.h>
+
+int main(int argc, char **argv) {
+    testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}