Add an assist handler "move_use_to_top_level" to move use statement to top level

[sgasho]

closes: #20326

fn main() {
     use std::collections::HashMap$0;
     let map = HashMap::new();
}

↓

use std::collections::HashMap;

fn main() {
    let map = HashMap::new();
}

Attributes and comments will be moved to the top level simultaneously.

example

fn main() {
    #[allow(unused)]
    use std::collections::HashMap$0;
    let map = HashMap::new();
}

↓

#[allow(unused)]
use std::collections::HashMap;

fn main() {
    let map = HashMap::new();
}