Implement or Add a open-source 2D native Delaunay Triangulator

[permcody]

Reason

MOOSE/libmesh doesn't have an license compatible way to build triangle or tet meshes. We need a native capability. This is one of the FY 22 NEAMS CRAB tasks.

Design

Evaluate and look at open-source options that are license compatible or implement one from scratch in MOOSE.

Impact

Will not impact existing capability but is critical for our reactor meshing capability moving forward.

[roystgnr]

Getting things summarized in writing:

libMesh/libmesh#3140 adds the start of the "native capability" here, at the libMesh level; it's not yet enough to be worth interfacing to Moose, but that should change when my next PR adds refinement support.

Longer term, I'll be helping the https://github.com/IllinoisRocstar/Nemosys guys integrate with Moose. Our current plan is "submodule, initially build-time configurable, using their .json format for input files"