chore(group_theory/perm/sign): speed up proofs (#3963)
fixes #3958
based on my completely unscientific test methods, this went from 40 seconds to ~~19~~ 17 seconds (on my laptop).
What I've done here is just `squeeze_simp`, but further speedup is definitely possible. Suggestions for what to do with `simp [*, eq_inv_iff_eq] at * <|> cc` are welcome, and should speed this file up a bit more.
