feat(analysis/convex): define convex hull (#1915)
* feat(analysis/convex): define convex hull
fixes #1851
* Fix compile
* Drop an unused argument
* Split line
* Rename some `_iff`s, drop others
* Mention `std_simplex` in the docs
* More docs
* Rename `α` to `ι`, other small fixes
* Use `range` instead of `f '' univ`
* More docs
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
