Fixed cons2entropy files and implemented entropy2cons for CompressibleEulerMulticomponent1D and CompressibleEulerMulticomponent2D

[teohyikhaw]

Fixes #1715 based on the equation on page 5 from this paper and equations on page 21 and 22 from Christoph Czernik's thesis.

[github-actions]

Review checklist

This checklist is meant to assist creators of PRs (to let them know what reviewers will typically look for) and reviewers (to guide them in a structured review process). Items do not need to be checked explicitly for a PR to be eligible for merging.

Purpose and scope

• The PR has a single goal that is clear from the PR title and/or description.
• All code changes represent a single set of modifications that logically belong together.
• No more than 500 lines of code are changed or there is no obvious way to split the PR into multiple PRs.

Code quality

• The code can be understood easily.
• Newly introduced names for variables etc. are self-descriptive and consistent with existing naming conventions.
• There are no redundancies that can be removed by simple modularization/refactoring.
• There are no leftover debug statements or commented code sections.
• The code adheres to our conventions and style guide, and to the Julia guidelines.

Documentation

• New functions and types are documented with a docstring or top-level comment.
• Relevant publications are referenced in docstrings (see example for formatting).
• Inline comments are used to document longer or unusual code sections.
• Comments describe intent ("why?") and not just functionality ("what?").
• If the PR introduces a significant change or new feature, it is documented in NEWS.md.

Testing

• The PR passes all tests.
• New or modified lines of code are covered by tests.
• New or modified tests run in less then 10 seconds.

Performance

• There are no type instabilities or memory allocations in performance-critical parts.
• If the PR intent is to improve performance, before/after time measurements are posted in the PR.

Verification

• The correctness of the code was verified using appropriate tests.
• If new equations/methods are added, a convergence test has been run and the results
  are posted in the PR.

Created with ❤️ by the Trixi.jl community.

[jlchan]

Looks good! I've added some suggestions for comments

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (f191444) 96.23% compared to head (2b43473) 96.24%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1767      +/-   ##
==========================================
+ Coverage   96.23%   96.24%   +0.01%     
==========================================
  Files         436      436              
  Lines       35210    35297      +87     
==========================================
+ Hits        33882    33969      +87     
  Misses       1328     1328              

Flag	Coverage Δ
unittests	96.24% <100.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[jlchan]

Looks like most of the changes to the tests are just due to formatting changes needed to pass CI.

I added two comments to the relevant sections that were actually changed.

[jlchan]

LGTM!

[jlchan]

Looks like some other PRs are observing failures in the MPI and threaded CI tests #1768. @sloede do you know if these are spurious?