Add `simple_seaice_partition` tool

[xylar]

This tool combines prepare_seaice_partitions and create_seaice_partitions and hard-codes values for many parameters to make it appropriate for LCRC (Anvil and Chrysalis).

[xylar]

Testing

I make a test environment:

mamba create -y -n mpas_dev mpas_tools "esmf=8.2.0=nompi_*"
mamba activate mpas_dev
python -m pip install -e conda_package/

Then, on Chrysalis, I ran:

simple_seaice_partitions -m /lcrc/group/e3sm/public_html/inputdata/ice/mpas-seaice/WC14to60E2r3/seaice.WC14to60E2r3.210210.nc -p mpas-seaice.graph.info.230427 -n 468

I end up with:

$ ls -lah
-rw-rw-r--  1 ac.xasay-davis cels 1.5M Apr 27 02:31 mpas-seaice.graph.info.230427.part.468

with the expected prefix, suffix and permissions.