mathlib3

97e01cda - feat(group_theory/free_abelian_group_finsupp): various equiv.of_free_*_group lemmas (#11469)

feat(group_theory/free_abelian_group_finsupp): various equiv.of_free_*_group lemmas (#11469) Namely `equiv.of_free_abelian_group_linear_equiv`, `equiv.of_free_abelian_group_equiv` and `equiv.of_free_group_equiv` Co-authored-by: Adam Topaz <github@adamtopaz.com>