feat(data/finset/basic): sdiff_val, disjoint_to_finset_iff_disjoint (#8168)
feat(data/finset/basic): sdiff_val, disjoint_to_finset_iff_disjoint (#8168)





Co-authored-by: Eric Wieser <da64e90baec5d084ce3d8e05f3b022ae6d118ff5@gmail.com>

leanprover-community/mathlib,leanprover-community/mathlib