Add test to take `Self` as an argument

tests/ui/needless_pass_by_value.rs

@@ -98,6 +98,7 @@ impl<T: Serialize, U> S<T, U> {
     fn baz(
         &self,
         _u: U,
+        _s: Self,
     ) {
     }
 }

tests/ui/needless_pass_by_value.stderr

@@ -122,3 +122,9 @@ error: this argument is passed by value, but not consumed in the function body
 100 |         _u: U,
     |             ^ help: consider taking a reference instead: `&U`
 
+error: this argument is passed by value, but not consumed in the function body
+   --> $DIR/needless_pass_by_value.rs:101:13
+    |
+101 |         _s: Self,
+    |             ^^^^ help: consider taking a reference instead: `&Self`
+