Add netcdf-cxx4 to the stack

[climbfuji]

JEDI uses netcdf-cxx4, which is not yet in the spack-stack environments.

[edwardhartnett]

netcdf-cxx is not a great idea. It is not fully maintained and does not contain the latest changes to netcdf-c.

Instead, C++ programmers should always use the netcdf-c library directly.

If JEDI wants to use netcdf-cxx, I suggest that some JEDI programmer spend a few weeks working on netcdf-cxx to bring it up to date, and understand that will be an on-going effort as the C library changes.

For example, netcdf-cxx does not support the new quantize functions, which allow lossy compression of data...

[climbfuji]

Good points, and certainly that is something we should look into. For now, in order to build the stack so that it works for JEDI needs, we'll add netcdf-cxx4 as a dependency for the jedi-environments only (i.e. if you build the ufs-weather-model environment, you won't get it).

[climbfuji]

@edwardhartnett I just realized that I mistakenly wrote netcdf-cxx in the issue, it's netcdf-cxx4. Your point still holds, we should migrate to netcdf-c, though. I created a corresponding issue in the soca-science repository, which is the only repository that I could find so far that uses netcdf-cxx4.