[FR] Code action: expand `||` into inferred closure params/return type at call site (e.g. `|a: u64| -> u32 { … }`)

Hello,

Do you think rust-analyzer can have this?

```rust
fn main(){
    // I write, and put cursor after ||
    here(||);
    // Then I want to rust-analyzer's code-action convert above line code to bellow code:
    here(|a:u64|-> u32 {
        
    });
}

fn here<F>(a: F)
where
    F: FnOnce(u64) -> u32,
{
    todo!()
}
```

Thank you.