Walk the pkg_ref class hierarchy to match a single subclass to a class path
get_pkg_ref_classes(x, classes = pkg_ref_class_hierarchy)A `character(n)` class path from `pkg_ref` down to the specified subclass, or `FALSE` if no path is found.
(`character(1L)`) A subclass, among those known in pkg_ref subclasses
(`list`) A class hierarchy, described using a named list. Defaults to `pkg_ref_class_hierarchy`.