add_MARBL (future): single column test with MARBL

[mnlevy1981]

There are two options for implementing a single-column test with MARBL enabled, each with its own set of downsides:

1. Use MOM6-examples
   • Need to update stand-alone build system to build with real MARBL and not add_MARBL/config_src/external/MARBL
   • Need to get forcing in a MOM-ish way
2. Introduce a single column grid for the CESM framework
   • Makes sense to start by porting one of the MOM6-example tests to CESM to make sure we configure MOM6 correctly for a 1D run
   • Need to introduce the new grid and all the associated domain / mapping files (perhaps less of a concern with NUOPC), this was a real headache with single-column POP

[mnlevy1981]

This issue came up in discussion at the MARBL software meeting because we were talking about Elizabeth Y's project, which is looking to implement a vertical migration term for zooplankton. She is interested in a single column model for that work.