Mean value in Zhang-Shu limiter on curved meshes

[andrewwinters5000]

This is a bug fix where all mesh types other than TreeMesh should compute the solution mean value u_mean including the element Jacobians. If this is not done, it is possible to lose conservation. Typically, the values from extra_analysis_errors = (:conservation_error,) in the AnalysisCallback should stay between 1e-13 to 1e-15. However, when one computes the incorrect value for u_mean on a curved mesh these conservation errors might increase to something between 1e-4 to 1e-8 (depending on the setup, how often the limiter is called, and how "warped" the mesh elements are).

[github-actions[bot]]

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Codecov Report

Attention: Patch coverage is 88.23529% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 96.15%. Comparing base (6e5ff49) to head (9a1d999).

Files	Patch %	Lines
src/solvers/dgsem_structured/dg.jl	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1945 +/- ## ========================================== - Coverage 96.15% 96.15% -0.00% ========================================== Files 454 454 Lines 36496 36509 +13 ========================================== + Hits 35092 35103 +11 - Misses 1404 1406 +2 ``` | [Flag](https://app.codecov.io/gh/trixi-framework/Trixi.jl/pull/1945/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=trixi-framework) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/trixi-framework/Trixi.jl/pull/1945/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=trixi-framework) | `96.15% <88.24%> (-<0.01%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=trixi-framework#carryforward-flags-in-the-pull-request-comment) to find out more.

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