IO prototype for History (and checkpoint)

[bena-nasa]

Following @tclune slides about the GeomIO, propose an abstract GEOM_IO layer that works with PFIO and a concrete grid class that only supports 2D, R4 output and would need a vast amount of generalization for all the different types/ranks/grid types (cube, lat/lon, etc)

Also add a geomCatagorizer function to instantiate the right GEOM_IO concrete class (that only supports grid cause there's nothing else we have besides grids).

Also adds a IOShared layer that has a bunch of utilities procedures that can be used for both history and checkpointing. For example a procedure to take a bundle and create a file metadata object (what we can so far...)

In the future I envision the we can also create a GEOM_IO layer that can implement the old gather/scatter strategy rather than using PFIO as the disk access for checkpoints.

Names need work, just wanted to get something committed and a draft.

Note this does work, I can now output multiple timestep files in History3G albeit only 2D gridded files.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Trivial change (affects only documentation or cleanup)

Checklist

• Tested this change with a run of GEOSgcm
• Ran the Unit Tests (make tests)

Description

Related Issue

[tclune]

Looks like a good start.

My inline comments are all about long term evolution of this layer. Nothing actionable at the moment.