Families of charts on a manifold are quasiordered by set inclusion of domains, ignoring coord_string. Subqosets can be defined by filtering by coord_string; an optional argument of Manifold.chart_poset will do this.

As in #31736, the poset quotients by the equivalence relation, so its elements are finite families of charts that have the same domain.

Depends on #31720

CC: @egourgoulhon @mjungmath

Component: manifolds

Issue created by migration from https://trac.sagemath.org/ticket/31771