Implement IDP mortars for IDP limiting

[bennibolm]

Implementation of IDP-compatible AMR based on the idea of Dmitri Kuzmin.

[github-actions]

Review checklist

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Purpose and scope

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Code quality

• The code can be understood easily.
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• There are no redundancies that can be removed by simple modularization/refactoring.
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Documentation

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Testing

• The PR passes all tests.
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• New or modified tests run in less then 10 seconds.

Performance

• There are no type instabilities or memory allocations in performance-critical parts.
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Verification

• The correctness of the code was verified using appropriate tests.
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  are posted in the PR.

Created with ❤️ by the Trixi.jl community.

[codecov]

Codecov Report

Attention: Patch coverage is 90.42553% with 54 lines in your changes missing coverage. Please review.

Project coverage is 96.72%. Comparing base (0fb8c65) to head (e4527e8).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/solvers/dgsem_tree/containers_2d.jl	46.97%	35 Missing ⚠️
src/solvers/dgsem/basis_lobatto_legendre.jl	81.40%	8 Missing ⚠️
src/time_integration/methods_SSP.jl	53.85%	6 Missing ⚠️
...llbacks_stage/subcell_limiter_idp_correction_2d.jl	98.64%	2 Missing ⚠️
src/solvers/dgsem/l2projection.jl	95.45%	2 Missing ⚠️
src/solvers/dgsem_tree/dg_2d_subcell_limiters.jl	99.53%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2305      +/-   ##
==========================================
- Coverage   96.80%   96.72%   -0.08%     
==========================================
  Files         495      496       +1     
  Lines       40917    41474     +557     
==========================================
+ Hits        39608    40114     +506     
- Misses       1309     1360      +51     

Flag	Coverage Δ
unittests	96.72% <90.43%> (-0.08%)	⬇️

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