WIP: Add local and global limiting for StructuredMesh

[bennibolm]

Adding the subcell local and global limiting support for StructuredMesh.

Getting the inverse Jacobian makes this PR a bit longer. That's because for TreeMesh, inverse_jacobian is fixed for one element, while it is different for each node for StructuredMesh.
To avoid something like

if mesh isa TreeMesh
    inverse_jacobian = cache.elements.inverse_jacobian[element]
end
for j in eachnode(dg), i in eachnode(dg)
    if mesh isa StructuredMesh
        inverse_jacobian = cache.elements.inverse_jacobian[i, j, element]
    end
    [...]
end

and also avoid unnecessary calls of inverse jacobian in TreeMesh simulations,
I dispatched for the mesh type and extracted the code [...] to an inner function.
After this PR, it will be straight forward to add support for P4estMesh.

For now, there is no support for non-conservative systems.

For now, I only added a free stream test including local and global limiting. Though, I think it doesn't make sense to merge another free stream elixir to main.
I will add a more interesting elixir (also for testing all new code) and delete the free stream elixir then.

[github-actions]

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[codecov]

Codecov Report

Attention: Patch coverage is 86.36364% with 33 lines in your changes are missing coverage. Please review.

Project coverage is 73.53%. Comparing base (01032aa) to head (c2e7496).

Files	Patch %	Lines
...rc/solvers/dgsem_structured/subcell_limiters_2d.jl	71.64%	19 Missing ⚠️
src/solvers/dgsem_tree/subcell_limiters_2d.jl	86.73%	13 Missing ⚠️
...llbacks_stage/subcell_limiter_idp_correction_2d.jl	95.24%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1739       +/-   ##
===========================================
- Coverage   96.31%   73.53%   -22.78%     
===========================================
  Files         440      443        +3     
  Lines       35797    35950      +153     
===========================================
- Hits        34476    26435     -8041     
- Misses       1321     9515     +8194     

Flag	Coverage Δ
unittests	73.53% <86.36%> (-22.78%)	⬇️

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[bennibolm]

Using new PR #1942 now.