build(rust): vendor googletest crate

third_party/crates/syn-2.0.119/tests/common/mod.rs

@@ -0,0 +1,6 @@
+#![allow(dead_code)]
+#![allow(clippy::module_name_repetitions, clippy::shadow_unrelated)]
+
+pub mod eq;
+pub mod parse;
+pub mod visit;