Factor `return`, `break` and `continue` from multiple branches

What it does

When all branches in a if/else[/if/…] or match are divergent, and several of them end with the same construct (return, break or continue), some things may be factored out, for example the most commonly used:

• return or break may be moved before the if or match if they have a payload
• in other cases, they may be moved after the if or match

Advantage

• Remove redundant keywords

Drawbacks

• May make the code harder to follow

Example

fn f(a: i32) -> i32 {
    if a > 3 {
        if a > 10 {
            return a;
        } else {
            return a+1;
        }
    }
    0
}

could be written as

fn f(a: i32) -> i32 {
    if a > 3 {
        return if a > 10 { a } else { a+1 };
    }
    0
}

No files, tests, or entry points are named. Start by examining the proposed Rust examples and existing Clippy handling for divergent if/match branches; done means eligible return, break, or continue constructs can be factored while preserving behavior.