Renaming MeshNetwork to NetworkMesh

[andrsd]

• This matches the file name
• This matches th enaming scheme (Structured, UnstructeredMesh, etc.)

[codecov]

Codecov Report

❌ Patch coverage is 0% with 29 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.58%. Comparing base (2fb646a) to head (bf7c05a).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/NetworkMesh.cpp	0.00%	29 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1007   +/-   ##
=======================================
  Coverage   76.58%   76.58%           
=======================================
  Files         155      155           
  Lines       10460    10460           
=======================================
  Hits         8011     8011           
  Misses       2449     2449           

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