feature: add RAJA kernel launches and basic CUDA support

[johnbowen42]

As of 2/8, this the main execution loops in domain_integral_kernels.hpp are compiling, passing very basic unit tests, and using a reasonable amount of memory for hexahedron or cubic element types. A couple main things remain to be done on this PR:

• Refactor boundary_integral_kernels.hpp by copying the existing RAJA implementation inside domain_integral_kernels.hpp
• Ensure existing CPU unit tests still pass

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 98.31288% with 11 lines in your changes are missing coverage. Please review.

Project coverage is 90.71%. Comparing base (b1bedfe) to head (98fc557).
Report is 10 commits behind head on develop.

Files	Patch %	Lines
.../serac/numerics/functional/element_restriction.cpp	0.00%	4 Missing ⚠️
...rics/functional/tests/functional_comparison_L2.cpp	71.42%	4 Missing ⚠️
...ac/numerics/functional/detail/quadrilateral_L2.inl	90.00%	1 Missing ⚠️
...rc/serac/numerics/functional/detail/segment_L2.inl	75.00%	1 Missing ⚠️
...c/serac/numerics/functional/detail/triangle_L2.inl	90.90%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1026      +/-   ##
===========================================
+ Coverage    90.63%   90.71%   +0.08%     
===========================================
  Files          162      162              
  Lines        14464    14633     +169     
===========================================
+ Hits         13109    13274     +165     
- Misses        1355     1359       +4     

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