Basic wrapper ESMF/MAPL access in python for access to state

[FlorianDeconinck]

Integration of Moist physics port back into the Fortran will require a first ESMF/MAPL shot at ESMF/MAPL.

For example, the code this code Aer Activation will require too much change in the Fortran and might be a prime example of using a direct python interface to the MAPL/ESMF state to retrieve the aero properties.

Parent: #44

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• Create a round-trip example pulling an array from the MAPL state, changing it's value in Python and reading back the value in Fortran
• Document usage and limitation
• Present to SI Team & gather feedback

[FlorianDeconinck]

Working branch: https://github.com/FlorianDeconinck/GEOSgcm_GridComp/tree/dsl/experimental/MAPLpyish