Add ide-assists, generate binary ops impl

[A4-Tacks]

Generate binary operation from assign operation.

Example

struct Int(i32);

impl core::ops::AddAssign$0<i32> for Int {
    fn add_assign(&mut self, rhs: i32) {
        self.0 += rhs;
        todo!()
    }
}

->

struct Int(i32);

impl core::ops::Add<i32> for Int {
    type Output = Self;

    fn add(mut self, rhs: i32) -> Self::Output {
        self += rhs;
        self
    }
}

impl core::ops::AddAssign<i32> for Int {
    fn add_assign(&mut self, rhs: i32) {
        self.0 += rhs;
        todo!()
    }
}