Make `manual_let_else` to lint `if let`s at the end of a function or loop

Description

Make manual_let_else to lint if lets at the end of a function or loop. For example:

fn reproducer(mut c: Vec<Option<i32>>) {
    let w = Some(0);
    if let Some(v) = w {
        c.push(Some(v));
        for mut i in c {
            i = i.filter(|x| *x > 0);
            if let Some(v) = i {
                let _ = v;
                println!("{v}");
            }
        }
    }
}

Changing the two if lets into let elses would result in more compact code and less nesting:

fn reproducer(mut c: Vec<Option<i32>>) {
    let w = Some(0);
    let Some(v) = w else {
        return;
    };
    c.push(Some(v));
    for mut i in c {
        i = i.filter(|x| *x > 0);
        let Some(v) = i else {
            continue;
        };
        let _ = v;
        println!("{v}");
    }
}

Version

rustc 1.95.0-nightly (c04308580 2026-02-18)
binary: rustc
commit-hash: c043085801b7a884054add21a94882216df5971c
commit-date: 2026-02-18
host: x86_64-unknown-linux-gnu
release: 1.95.0-nightly
LLVM version: 22.1.0

Additional Labels

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