Liu-Zhang part 3

[jlchan]

Should be considered only after #3066

TODO:

• Base.show specialization (moved to Liu-Zhang part 3  #3100)
• try computing the cell averages and the local volumes together (see Liu-Zhang global cell average limiter (part 1, advection) #3063 (comment)). This probably makes more of a difference for P4estMesh, so I think we should defer it for Liu-Zhang part 3  #3100)

[github-actions]

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[codecov]

Codecov Report

❌ Patch coverage is 77.44361% with 60 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.78%. Comparing base (099f4e1) to head (eed8cff).

Files with missing lines	Patch %	Lines
src/callbacks_stage/positivity_liu_zhang.jl	42.86%	24 Missing ⚠️
.../callbacks_stage/admissible_projection_euler_1d.jl	81.91%	17 Missing ⚠️
.../callbacks_stage/admissible_projection_euler_2d.jl	80.00%	16 Missing ⚠️
...1d_dgsem/elixir_euler_leblanc_limiter_liu_zhang.jl	86.36%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3100      +/-   ##
==========================================
- Coverage   96.88%   96.78%   -0.10%     
==========================================
  Files         652      657       +5     
  Lines       50179    50437     +258     
==========================================
+ Hits        48615    48813     +198     
- Misses       1564     1624      +60     

Flag	Coverage Δ
unittests	96.78% <77.44%> (-0.10%)	⬇️

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