ENH:Refactor due to aeva smtk slicer extension

function smtk::session::aeva::createCellForData and its helping function relateToParent() have been moved to Predicates.

VTK module WrappingPythonCore has been added to pybind11 to work with building with Slicer's VTK and SMTK.

Also addressess issue #3 (closed) .