Implement the first real test of gpt4all-chat (#3116)

Signed-off-by: Jared Van Bortel <jared@nomic.ai>

gpt4all-chat/tests/cpp/basic_test.cpp

@@ -0,0 +1,5 @@
+#include <gtest/gtest.h>
+
+TEST(BasicTest, TestInitialization) {
+    EXPECT_TRUE(true);
+}

gpt4all-chat/tests/cpp/test_main.cpp

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