Tracking issue for `Result::map_or`

PR #66292 added `Result::map_or` with implementation:
```rust
impl<T, E> Result<T, E> {
    pub fn map_or<U, F: FnOnce(T) -> U>(self, default: U, f: F) -> U {
        match self {
            Ok(t) => f(t),
            Err(_) => default,
        }
    }
}
```

