test: rename to tests/ for Rust integration test compatibility

tests/wrappers/point-test.rs

@@ -0,0 +1,10 @@
+#[test]
+mod tests {
+    use arc_core::ffi::point::Point;
+
+    fn point_creation() {
+        let p = Point::new(1.0, 2.0, 3.0);
+        let coords = p.coordinates();
+        assert_eq!(coords, (1.0, 2.0, 3.0));
+    }
+}