Remove POLYFEM_WITH_REMESHING CMake Option

[zfergus]

Make remeshing solely a runtime option.

(also update libigl)

[zfergus]

Windows CMake fails with this error:

CMake Error at C:/Program Files/CMake/share/cmake-3.27/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
  Could NOT find Filesystem (missing: _found)
Call Stack (most recent call first):
  C:/Program Files/CMake/share/cmake-3.27/Modules/FindPackageHandleStandardArgs.cmake:600 (_FPHSA_FAILURE_MESSAGE)
  C:/Users/runneradmin/.cache/CPM/h5pp/9a95839ec50c29d5555bd20b5f1e69a49e850a6f/cmake/modules/FindFilesystem.cmake:251 (find_package_handle_standard_args)
  C:/Users/runneradmin/.cache/CPM/h5pp/9a95839ec50c29d5555bd20b5f1e69a49e850a6f/cmake/SetupDependencies.cmake:11 (find_package)
  C:/Users/runneradmin/.cache/CPM/h5pp/9a95839ec50c29d5555bd20b5f1e69a49e850a6f/CMakeLists.txt:82 (include)

[codecov]

Codecov Report

Attention: Patch coverage is 25.00000% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 65.37%. Comparing base (609149f) to head (e2b5b39).
Report is 34 commits behind head on main.

❗ Current head e2b5b39 differs from pull request most recent head acb87ae

Please upload reports for the commit acb87ae to get more accurate results.

Files	Patch %	Lines
src/polyfem/utils/RefElementSampler.cpp	0.00%	2 Missing ⚠️
src/polyfem/quadrature/PolygonQuadrature.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #253      +/-   ##
==========================================
+ Coverage   64.13%   65.37%   +1.23%     
==========================================
  Files         281      262      -19     
  Lines       34301    32279    -2022     
==========================================
- Hits        21999    21102     -897     
+ Misses      12302    11177    -1125     

Flag	Coverage Δ
polyfem	65.37% <25.00%> (+1.23%)	⬆️

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.