Add numerical support for other real types (fluxes)

[huiyuxie]

Continue #1909. This PR would finish all the primary work for #591 with single precision float numbers (Float32). Other helper work will continue here #1948.

Tasks:

• numerical_fluxes
• fix related broken tests

[github-actions]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.52%. Comparing base (5f5a232) to head (0bd8fe1).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2021      +/-   ##
==========================================
+ Coverage   94.04%   94.52%   +0.48%     
==========================================
  Files         462      462              
  Lines       37076    37055      -21     
==========================================
+ Hits        34867    35026     +159     
+ Misses       2209     2029     -180     

Flag	Coverage Δ
unittests	94.52% <100.00%> (+0.48%)	⬆️

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[ranocha]

Thanks!