Enable Cross-Platform Support for FindNetCDF.cmake

[amstokely]

Summary

This PR rewrites the FindNetCDF.cmake file to simplify its logic and ensure it works on both Linux and macOS. The new version relies solely on the output of the nc-config, ncxx4-config, and nf-config tools provided by the NetCDF C, C++, and Fortran libraries.

Motivation

The current FindNetCDF.cmake script fails to detect NetCDF installations provided by Homebrew on macOS.

Key Improvements

• Fully relies on the netcdf-config tools, which are the recommended way to query NetCDF build details.
• Works with NetCDF installations from multiple sources:
  • Linux (tested with Spack and manual source builds)
  • macOS (tested with Homebrew installations)
• Correctly handles include directories, library directories, and link flags,

Testing

• Linux: Confirmed working with:
  • Spack-installed NetCDF (C, C++, Fortran)
    - Build log
  • Manually built and installed NetCDF
• macOS: Confirmed working with:
  • Homebrew-installed NetCDF (C, C++, Fortran)

[mgduda]

Ideally, we could have determined why exactly the current FindNetCDF.cmake script doesn't work with homebrew-installed netCDF libraries and applied some targeted changes; but if this rewrite works, that's sufficient.