Enhance SamplingShaper so it can work on low order Blueprint meshes

[BradWhitlock]

This PR resolves #1692 so the quest::SamplingShaper can operate on Blueprint low order meshes.

• Moved SamplingShaper MFEM state into a state object that can be used among helper routines
• Added a BlueprintState object to support Blueprint state
• Enhanced various methods to operate on both types of state, templating as needed
• Separated "shaping_helpers.{cpp,hpp}" into MFEM and Blueprint files
• Quadrature enhancements: an enum and some more methods to generate quadrature points
• Blueprint sampling will generate sample points at quadrature as with HO and then sample shapes at those points, ultimately converting to material fields on the Blueprint mesh
• Changed CMake logic so SamplingShaper can be built when either MFEM or Conduit (or both) are present -- enables a shaper that works without MFEM
• When MFEM is present, we can shape MFEM contours onto Blueprint mesh in 2D
• Enhanced shaping_driver so it can work with blueprint only mode, currently selected via inline blueprint mesh
• Added a test of Blueprint-only mode for STL spheres
• Made IntersectionShaper use BlueprintState where needed
• Enhancements that allow shaping on Blueprint meshes via conduit::Node or via sidre::Group.

[jcs15c]

I think this method could use a brief doxygen header to explain what it does, even if it isn't user-facing.

[BradWhitlock]

Done

[jcs15c]

Now that there's a lot of quadrature rules to keep track of, do you think it's generally useful enough to have a helper function like get_exact_degree(numerics::QuadartureType, npts)? Even if it isn't necessary to actually execute it most of the time, its source code could provide a useful compendium of which rules evaluate which order polynomials.

[BradWhitlock]

I had codex move code into a get_exact_degree helper function and update the tests.