mathlib3

ecdb1383 - feat(category/equiv_functor): type-level functoriality w.r.t. equiv (#2255)

feat(category/equiv_functor): type-level functoriality w.r.t. equiv (#2255) * feat(data/equiv/functor): bifunctor.map_equiv * start * sketch of equiv_functor * update * removing unimpressive inhabited example; easier later * omit * revert unnecessary change * fix doc-string * fix names * finish fix Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>