Rollup merge of #139778 - reddevilmidzy:add-success-test, r=lcnr

Add test for issue 34834

closes: #34834

This PR adds a UI test for a case where a trait with an associated type using a higher-ranked trait bound (HRTB) failed to compile in Rust 1.55.0 but succeeded starting from 1.56.0.

```rust
pub trait Provides<'a> {
    type Item;
}

pub trait Selector: for<'a> Provides<'a> {
    type Namespace: PartialEq + for<'a> PartialEq<<Self as Provides<'a>>::Item>;

    fn get_namespace(&self) -> <Self as Provides>::Item;
}

pub struct MySelector;

impl<'a> Provides<'a> for MySelector {
    type Item = &'a str;
}

impl Selector for MySelector {
    type Namespace = String;

    fn get_namespace(&self) -> &str {
        unimplemented!()
    }
}

fn main() {}
```

* ❌ [compile fail (rustc: 1.55.0)](https://godbolt.org/z/T1jY1Ebo6)
* ⭕ [compile pass (rustc: 1.56.0)](https://godbolt.org/z/e4jo11Ma7)

Author: matthiaskrgr