feat(netcdf): export and input stress period array support

[mjreno]

NetCDF support for input and export stress period array data:

• ugrid and structured netcdf files supported
• primarily focused on index layer variable based packages (evta, rcha)
• will need minor updates to support non-index layer variable based packages
• layer variable is stored as a layer variable (ncpl) in the netcdf file
• to support visualization, period data variables are stored fully gridded in the netcdf file
• added use of modflow6_iper and modflow6_iaux internal attributes
• netcdf documentation will be in a separate, forthcoming PR

Checklist of items for pull request

• Replaced section above with description of pull request
• Added new test or modified an existing test
• Ran ruff on new and modified python scripts in .doc, autotests, doc, distribution, pymake, and utils subdirectories.
• Formatted new and modified Fortran source files with fprettify
• Added doxygen comments to new and modified procedures
• Updated definition files
• Removed checklist items not relevant to this pull request

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