Rollup merge of #137825 - estebank:rtn-sugg-2, r=compiler-errors

Provide more context on resolve error caused from incorrect RTN

When encountering a resolve E0575 error for an associated method (when a type was expected), see if it could have been an intended return type notation bound.

```
error[E0575]: expected associated type, found associated function `Trait::method`
  --> $DIR/bad-inputs-and-output.rs:31:36
   |
LL | fn foo_qualified<T: Trait>() where <T as Trait>::method(i32): Send {}
   |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^ not a associated type
   |
help: you might have meant to use the return type notation syntax
   |
LL - fn foo_qualified<T: Trait>() where <T as Trait>::method(i32): Send {}
LL + fn foo_qualified<T: Trait>() where T::method(..): Send {}
   |
```

Built on top of #137824, only second commit is relevant for review.

r? ````````@compiler-errors````````

Author: compiler-errors