Activate fluid models

[dkachuma]

This PR activates some fluid models in MultiFluidSelector.hpp only for CPU builds. The issue is that when activated for CUDA builds, these extra models cause compilation failures for some of the GHA pipelines. These are therefore currently being activated only for non-device builds.

• Some dangling debugging code is also cleaned up.
• A unit test is activated to test the different fluid models.

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 53.70%. Comparing base (0f53ecd) to head (9449600).

Files	Patch %	Lines
...onents/constitutive/fluid/multifluid/PVTDriver.cpp	50.00%	1 Missing ⚠️
...ompositional/models/NegativeTwoPhaseFlashModel.hpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3123   +/-   ##
========================================
  Coverage    53.70%   53.70%           
========================================
  Files         1010     1010           
  Lines        85637    85639    +2     
========================================
+ Hits         45990    45993    +3     
+ Misses       39647    39646    -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.