fix(stg): Use CalculateElementLengths for ICs

refactor: Use utils in setupgeo_helpers.h

Includes adding Norm2 and GradUnpack2

docs(qdata): Minor fix to Setup2D_3Dcoords docstring

refactor(qdata): SetupBoundaryGradient use helpers

refactor(qdata): Have ND QFs return error code

So that the more specific ones just `return Qdata*_ND(...);`.
Behavior more inline with how the state variable QFunction error codes
are handled.

refactor(div F_diff): Change Setup arguments

feat(div F_diff): Use function pointers for RHS Op creation

feat: Implement divergence of diffusive flux

feat: Add MatMatNM and GradUnpackN to utils

- Implemented in `StatePhysicalGradientFromReference`

refactor: Move N-dimensional QdataUnpack* to utils.h

feat: Add jac_data_size_vol

- Allows non-Jacobian examples to not have to set zeros to it's inputs
- Removes the need for `uses_newtonian` (newtonian itself can not add
the extra term for IDL)

refactor: norm -> normal, and others

chore: Move to Apache-2.0 OR BSD-2-Clause

qf: Add Norm3 utility function

stg: Create separate CalculateElementLengths function

- This also centralizes the note regarding the functions failure on
tetrahedral elements

bc: Implement 3D dXdx for strong STG

- Used for determining element size in STG calculation

boundary: Add cell-to-face basis routines

refactor: Make StateToQ array zeroing consistent

fix: Address GCC compiler warnings

- GCC was concerned that `q` in the STG code was being used
uninitialized
- GCC was also concerned that PetscViewerBinaryRead doesn't guarantee
that the value

fix: Address GCC compiler warnings

- GCC was concerned that `q` in the STG code was being used
uninitialized
- GCC was also concerned that PetscViewerBinaryRead doesn't guarantee
that the value is being set (which is always is...)

show more ...

Merge pull request #1606 from CEED/jrwrigh/ken_stg_additions

fluids: Add dyScale and dz to STG options

refactor(fluids): Rename norm -> normal in freestream

Also remove comment references to potential energy, which is no longer
included in the total energy definition.

fix(fluids): Correct Riemann HLL *_fwd functions

fluids: Add h_scale_factor to STG options

fluids: Remove entropy variable from State struct

fluids: Proliferate entropy variables, add test

Co-authored-by: Zach Atkins <zacharyjayhawk@gmail.com>