Upwind SBP on curved meshes

[andrewwinters5000]

This PR replaces #1295 . Implementation of the upwind FDSBP solver on unstructured curvilinear meshes. The solver converges for all available splittings and is free-stream preserving provided the boundary polynomial order from the mesh file, i.e., mesh_polydeg is half the boundary closure order of the SBP operator.

[github-actions]

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[codecov]

Codecov Report

Attention: Patch coverage is 97.97297% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 96.29%. Comparing base (e205b06) to head (40f6547).

Files	Patch %	Lines
src/solvers/fdsbp_unstructured/fdsbp_2d.jl	92.11%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1857      +/-   ##
==========================================
+ Coverage   96.28%   96.29%   +0.01%     
==========================================
  Files         438      438              
  Lines       35386    35519     +133     
==========================================
+ Hits        34071    34201     +130     
- Misses       1315     1318       +3     

Flag	Coverage Δ
unittests	96.29% <97.97%> (+0.01%)	⬆️

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[ranocha]

Thanks a lot! Please find below some comments and questions.

[ranocha]

Suggested change

	# Note, one must set `xmin=-1` and `xmax=1` due to the reuse
	# of interpolation routines from `calc_node_coordinates!` to create
	# the physical coordinates in the mappings.
	# TODO: FDSBP
	# Note, one must set `xmin=-1` and `xmax=1` due to the reuse
	# of interpolation routines from `calc_node_coordinates!` to create
	# the physical coordinates in the mappings.

That's fine for now but we should keep track of it so that someone can improve this later. I added it to the list in #1284

[andrewwinters5000]

Okay, that sounds reasonable. I thought about throwing an error if a user attempts to set anything different for the xmin and xmax values. Would this maybe be overkill? Alternatively, we could maybe add "under the hood" an affine map of the user desired xmin and xmax to the [-1,1] interval. However, I am hot sure if this would mess with plotting or post processing later.

[ranocha]

Thanks a lot! I will merge this and release a new Trixi.jl version when CI passes (whereever it can...)

[andrewwinters5000]

Thanks a lot! I will merge this and release a new Trixi.jl version when CI passes (whereever it can...)

Great, thanks! It is nice to have finally figured out all this curvilinear upwind stuff. I will close my old PR and delete that (very stale) branch.