new lint for &str to String conversion

There are a few different ways to convert from a &str to a String:

fn main() {
    let _: String = "hello".to_owned();
    let _: String = "hello".to_string();
    let _: String = "hello".into();
    let _: String = String::from("hello");
    let _: String = format!("hello");
}

Without going into a discussion about which is the best (this lint has been deprecated), I think a lint to ensure the same one is used throughout a crate would be interesting.

This could be done either through configuration, or by keeping stats on which is used and then emit warning for the non majority one.

I can work on it, but wanted to have a general point of view before. What do you think ?

Start with the issue's four Rust conversion examples and review the deprecated str_to_string lint linked in the description. Resolve whether the lint should use explicit configuration or infer the crate's majority style, then define how non-majority conversions are identified and what behavior marks the work complete.