feat: Add Unittest example

tests/test_example.cpp

@@ -0,0 +1,14 @@
+#include "unity.h"
+
+void setUp() {}
+void tearDown() {}
+
+void test_example() {
+    TEST_ASSERT_TRUE(true);
+}
+
+auto main() -> int {
+    UNITY_BEGIN();
+    RUN_TEST(test_example);
+    return UNITY_END();
+}