Function format_rename_path 

pub fn format_rename_path(old: &str, new: &str) -> String

Format a rename pair using Git’s compact path format.

Examples:

• a/b/c → c/b/a → a/b/c => c/b/a
• c/b/a → c/d/e → c/{b/a => d/e}
• c/d/e → d/e → {c/d => d}/e
• d/e → d/f/e → d/{ => f}/e