Fixes #1618. Add zstandard support

[mathomp4]

Types of change(s)

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Trivial change (affects only documentation or cleanup)
• Refactor (no functional changes, no api changes)

Checklist

• Tested this change with a run of GEOSgcm
• Ran the Unit Tests (make tests)

Description

This PR adds support for zstandard compression in History via zstandard_level.

Much like netCDF quantize support, if netCDF-C wasn't built with zstandard support, then MAPL will not allow a user to set zstandard_support. We also prevent a user from setting both deflate and zstandard_level at the same time. Also, two new ExtData tests are added.

NOTE: At the moment, this support is only available via Spack builds of MAPL (and GEOS). The reason is that zstandard support in netCDF-C is only available via shared library (because it uses HDF5 plugins). For historic reasons, ESMA Baselibs uses static HDF5, netCDF, etc.

cc: @edwardhartnett

Related Issue

Closes #1618

[mathomp4]

Yup. This is currently not working. I've done something wrong, but not sure what yet. Turns out, enabling zstandard doesn't actually enable it! Bug hunting time.

ETA: Bug is found! Huzzah!