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)
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