Add ide-assist: remove_reference

[A4-Tacks]

Remove parameter reference.

Example

fn foo($0state: &bool) {
    if *state {}
}
fn bar() {
    let state = true;
    foo(&state);
}

->

fn foo(state: bool) {
    if state {}
}
fn bar() {
    let state = true;
    foo(state);
}