Replace push_str with the corresponding operator

What it does

This (probably pedantic) link suggests to replace calls to .push_str() with the corresponding operator.

Advantage

Shorter and more to the point code. And scripting language programmerer (as Python) are used to using operators for this.

Drawbacks

I don't know if there are drawbacks.

Example

fn main() {
    let mut msg = String::from("Hello");
    msg.push_str(", world");
    println!("{msg}"); // Hello, world
}

Could be written as:

fn main() {
    let mut msg = String::from("Hello");
    msg += ", world";
    println!("{msg}"); // Hello, world
}

No files or tests are named. Start by searching the repository for existing handling of String::push_str and related lint tests, then determine the appropriate entry point for this proposal. Done means the lint recognizes the applicable calls, offers the corresponding operator, and has coverage for the accepted cases and any identified drawbacks.