internal: add cloning macro fixture

Macro that deep clone the tokens but otherwise preserves source
locations and hygiene info is an interesting case for IDE support. Lets
have this, although we don't actively use it at the moment.

crates/proc_macro_srv/src/tests/mod.rs

@@ -42,6 +42,19 @@ fn test_fn_like_macro() {
     );
 }
 
+#[test]
+fn test_fn_like_macro2() {
+    assert_expand(
+        "fn_like_clone_tokens",
+        r#"ident, []"#,
+        expect![[r#"
+            SUBTREE $
+              IDENT   ident 4294967295
+              PUNCH   , [alone] 4294967295
+              SUBTREE [] 4294967295"#]],
+    );
+}
+
 #[test]
 fn test_attr_macro() {
     // Corresponds to
@@ -70,6 +83,7 @@ fn list_test_macros() {
         fn_like_noop [FuncLike]
         fn_like_panic [FuncLike]
         fn_like_error [FuncLike]
+        fn_like_clone_tokens [FuncLike]
         attr_noop [Attr]
         attr_panic [Attr]
         attr_error [Attr]