Fix loses label for convert_for_to_while_let

[A4-Tacks]

Fixes:

• loses label for convert_while_to_loop and convert_for_to_while_let
• loses attributes for convert_while_to_loop and convert_for_to_while_let
• bad indent for convert_while_to_loop

Examples

fn main() {
    #[allow(unused)]
    #[deny(unsafe_code)]
    'a: while$0 let Some(x) = cond {
        foo();
        break 'a;
    }
}

Before this PR:

fn main() {
    loop {
        if let Some(x) = cond {
            foo();
            break 'a;
        } else {
            break;
        }
    }
}

After this PR:

fn main() {
    #[allow(unused)]
    #[deny(unsafe_code)]
    'a: loop {
        if let Some(x) = cond {
            foo();
            break 'a;
        } else {
            break;
        }
    }
}

---

fn main() {
    let mut x = vec![1, 2, 3];
    #[allow(unused)]
    #[deny(unsafe_code)]
    'a: for $0v in x {
        v *= 2;
        break 'a;
    };
}

Before this PR:

fn main() {
    let mut x = vec![1, 2, 3];
    let mut tmp = x.into_iter();
    while let Some(v) = tmp.next() {
        v *= 2;
        break 'a;
    };
}

After this PR:

fn main() {
    let mut x = vec![1, 2, 3];
    let mut tmp = x.into_iter();
    #[allow(unused)]
    #[deny(unsafe_code)]
    'a: while let Some(v) = tmp.next() {
        v *= 2;
        break 'a;
    };
}