Add Clayton-Engquist boundary condition for acoustic wave

[SouzaEM]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 88.57143% with 4 lines in your changes missing coverage. Please review.

Project coverage is 84.34%. Comparing base (96a1aad) to head (625f5da).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
...yro/solvers/acoustic_solver_construction_no_pml.py	77.77%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #134      +/-   ##
==========================================
+ Coverage   84.31%   84.34%   +0.02%     
==========================================
  Files          58       59       +1     
  Lines        3902     3935      +33     
==========================================
+ Hits         3290     3319      +29     
- Misses        612      616       +4     

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[Olender]

Good idea having the default top be false

[Olender]

We need to ensure that if we use other meshing tools in the future, we always follow the numbering scheme used here (top=1, bottom=2, etc.). In the future, it may be helpful to add a check after loading the mesh to verify this consistency.

[SouzaEM]

As this verification is also necessary for elastic waves, I will merge this pull request and open a new issue for making sure the numbering scheme is appropriate for the mesh.