feat(algebraic_topology): cosimplicial objects (#7614)
Dualize the existing API for `simplicial_object` to provide `cosimplicial_object`, and move the contents of LTE's `for_mathlib/simplicial/augmented.lean` to mathlib.
Co-authored-by: Adam Topaz <github@adamtopaz.com>
Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
