Add numerical support of other real types (linear_advection)

[huiyuxie]

Continue #1909.

Linear advection seems easier to review and merge, so I do these first in equations.

Tasks:

• linear_scalar_advection 1d, 2d, 3d
• unit tests for above

[github-actions]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.16%. Comparing base (6bb0be5) to head (23c0050).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1971      +/-   ##
==========================================
+ Coverage   96.15%   96.16%   +0.01%     
==========================================
  Files         460      460              
  Lines       36949    36958       +9     
==========================================
+ Hits        35527    35539      +12     
+ Misses       1422     1419       -3     

Flag	Coverage Δ
unittests	96.16% <100.00%> (+0.01%)	⬆️

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[ranocha]

Thanks a lot! This looks quite good already. Could you please add some unit tests?

[huiyuxie]

Okay

[huiyuxie]

Ready for final review @ranocha :/

[ranocha]

Thanks!