Improve case with one named, one anonymous lifetime parameter - SubSupConflict Errors

Currently in  #42669, we are handling only ConcreteFailure RegionResolution Errors.  We need to detect and improve the error message for SubSupConflict Error as well.
```rust
struct Foo {
  field: i32
}
impl Foo{

  fn foo2<'a>(&self, x: &'a i32) -> &'a i32 {
    if true { &self.field } else { x }
  }
}
```
cc @nikomatsakis  