Add regression tests for all models

[GiudGiud]

Syntax checks are a good start, but they dont prevent the models from breaking Even a RunApp which actually runs the input will not prevent erroneous results. Only comparisons to known data points are robust enough. These are unfortunately too expensive for most inputs, so only a few time steps will be compared. And only using CSV output to avoid large files in the repository

• [x] MSFR Griffin-Pronghorn
• [ ] MSFR Nek (too expensive?)
• [x] MSRE SAM
• [x] PBMR-400
• [ ] mHTGR SAM
• [x] FHR Griffin-Pgh
• [ ] FHR Nek (too expensive?)
• [x] FHR SAM
• [x] mrad (coupled multiphysics excluded for now, too expensive)
• [x] SFR griffin-bison