Add Polygon/Polyhedron NSIDED/NFACED ExodusII output

[ConnorOuellette]

Summary

This adds ExodusII output support for libMesh’s arbitrary polygon and polyhedron elements:

• writes C0POLYGON elements as Exodus NSIDED blocks
• writes C0POLYHEDRON elements as Exodus NFACED blocks
• emits the associated face block, face-node connectivity, face counts, element-face connectivity, and element face counts needed for NFACED output

Notes

• If using ParaView, the default IOSS Reader does not support polygonal/polyhedral input. Please use the Legacy Exodus Reader.
• Fixed an error with build_cube() where corner nodes were scaled twice