Clean up and fix hypersurface utils #870
Description
Likely as a result of utils/hypersurface/hypersurface.py containing ~2.5k lines, from a cursory glance at its pylint report, there are at least 20 non-trivial TODOs and some bugs (e.g. collections.Mapping and collections.Sequence).
utils/hypersurface/hypersurface_interpolator.py is a similar mess. It even says so itself.