Add ncremap parallel exec

[xylar]

This is needed on compy (and possibly other places) to handle ESMF built with system MPI.

Update compy examples for new system ESMF support.

Update to 1.4.0rc3

[xylar]

Testing

I ran with E3SM-Unified 1.5.0rc2 with ESMF build with system MPI on Compy. I replaced pyremap with 0.0.13 (MPAS-Dev/pyremap#39) and MPAS-Analysis with this branch. I used srun --mpi=pmi2, as in the updated example for compy. With these changes, I was able to run, whereas, Compy gets stuck on ESMF_RegridWeightGen and ncremap calls without this change.

I ran the usual test suite on Chrysalis (not using system ESMF) and all passed:
https://web.lcrc.anl.gov/public/e3sm/diagnostic_output/ac.xylar/analysis_testing/chrysalis/add_ncremap_parallel_exec/