Support netcdf-4 compression & chunking

[anton-seaice]

Currently support for netcdf-4 features in CICE is pretty limited. Netcdf supports chunking and compression.

When implemented, #862 will let CICE standalone output netcdf-4 files when it is built using the io_pio directory. (The nuopc driver also has options to configure netcdf-4)

It would be good to add support for the extra features like chunking and compression (we would use in it in the ACCESS model). This would need a namelist option (e.g. netcdf4_options) which would be something like:

netcdf4_options = deflate_level, chunksize_x, chunksize_y

This option would only be relevant if the iotype is one of the netcdf4 types (netcdf4c or netcdf4p), otherwise it would be ignored.

For code changes, in all the places pio_def_var() is used we would need to add:

• add pio_def_var_deflate() if deflate_level is set (https://ncar.github.io/ParallelIO/group___p_i_o__def__var.html)
• pio_def_var_chunking() if chunksize_x or chunksize_y are set (https://ncar.github.io/ParallelIO/group___p_i_o__def__var.html)

This change would mean the io_pio build is ahead of the io_netcdf build. Builds using the io_netcdf files would only be using netcdf-3 / classic.

[apcraig]

See #862