Add dual-polar VR grid to ccs_config

[adamrher]

This is the ccs_config PR for installing the spectral-element dual polar grid. The CAM PR is here ESCOMP/CAM#979.

I'm going to ask we call this the 'POLARCAP' grid. So the component_grids_nuopc.xml entry would look like:

  <domain name="ne0np4.POLARCAP.ne30x4">
    <nx>186194</nx> <ny>1</ny>
    <mesh>/glade/work/aherring/grids/var-res/ne0np4.POLARRES.ne30x4/grids/polarcap/POLARCAP_ne30x4_np4_MESH_cdf5.nc</mesh>
    <desc>ne0np4.POLARCAP.ne30x4 is a Spectral Elem 1-deg grid with a 1/4 deg refined region over the Arctic and Antarctica:</desc>
    <support>Test support only</support>
  </domain>

We are aiming to complete this installation for the CESM3 release.