mathlib3

b332507c - feat(data/int/basic): Forward direction of `is_unit_iff_nat_abs_eq` (#14516)

feat(data/int/basic): Forward direction of `is_unit_iff_nat_abs_eq` (#14516) This PR adds the forward direction of `is_unit_iff_nat_abs_eq` as a separate lemma. This is useful since you often have `is_unit n` as a hypothesis, and `is_unit_iff_nat_abs_eq.mp hn` is a bit of a mouthful. Co-authored-by: tb65536 <tb65536@users.noreply.github.com>