update(optimize_splitting_mask): add active_only flag

[jlarsen-usgs]

• when True, the active_only flag creates an adjacency graph for metis that only includes active cells. Inactive cell membership is later assigned a model via nearest neighbor.
• fix layer count for UnstructuredGrid splitting in optimize_splitting_mask and reconstruct_array
• add options parameter to support pymetis.Options input
• add optional verbose flag to optimize_splitting_mask

Closes #2576

[codecov]

Codecov Report

❌ Patch coverage is 90.69767% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.5%. Comparing base (556c088) to head (00cca4b).
⚠️ Report is 49 commits behind head on develop.

Files with missing lines	Patch %	Lines
flopy/mf6/utils/model_splitter.py	88.0%	6 Missing ⚠️
flopy/discretization/structuredgrid.py	94.3%	4 Missing ⚠️
flopy/discretization/grid.py	75.0%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2600      +/-   ##
===========================================
+ Coverage     55.5%    72.5%   +17.0%     
===========================================
  Files          644      667      +23     
  Lines       124135   128860    +4725     
===========================================
+ Hits         68947    93486   +24539     
+ Misses       55188    35374   -19814     

Files with missing lines	Coverage Δ
flopy/discretization/grid.py	75.7% <75.0%> (-0.3%)	⬇️
flopy/discretization/structuredgrid.py	51.1% <94.3%> (+3.7%)	⬆️
flopy/mf6/utils/model_splitter.py	65.4% <88.0%> (-9.5%)	⬇️

... and 551 files with indirect coverage changes

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[jlarsen-usgs]

Note: ruff's linting is failing on > 300 errors. These errors are for files that have not been edited in this PR. Has something about how we are linting changed and should the entire repository be linted in a separate PR? It doesn't seem proper to fold those changes in this PR.

[mwtoews]

Recent changes have been overwritten, causing the unrelated lint errors. The PR should only target rewriting specific sections of relevant files, not overwriting entire files (loosing previous edits).

[jlarsen-usgs]

Did not notice that there was changes in the pyproject.toml, reverted files and re-committed

[wpbonelli]

@jlarsen-usgs those failing notebooks are skipped on mac and windows as of 89b045f