Implement `std::ops` traits to return arbitrary output defined as associated type

[ironcev]

When std::ops traits were originally defined, we didn't support associated types. Therefore, all traits, like Add or Sub were defined as, e.g.:

pub trait Add {
    fn add(self, rhs: Self) -> Self;
}

This restricts us in API flexibility. E.g., in std::time::Time, adding Time and Duration requires having add on impl Time.

The proposal is to migrate to Rust-like traits that have the result type specified as associated type. E.g.:

pub trait Add<Rhs> {
    type Output;

    fn add(self, rhs: Rhs) -> Self::Output;
}