mathlib

71cf2908 - feat(algebra/group/commute): add `units.left/right_of_mul` (#17595)

feat(algebra/group/commute): add `units.left/right_of_mul` (#17595) * add `units.left_of_mul`, `units.right_of_mul`, `units.of_pow`, `units.of_pow_eq_one`; * add `is_prime_pow.not_unit`, `is_unit.not_is_prime_pow `; * golf.