Build SHiELD with the full FMSCoupler and SHiEMOM (SHIELD+MOM6)

This PR allows building SHiELD with the full coupler from FMSCoupler. A new compile option 'shieldfull' is added to allow that functionality. The old shield coupler is still maintained when compiling with the option 'shield' (still the default option).

This PR also allows checking out MOM/SIS2 files and compiling them as libraries then linking them to SHiELD. The new model is called SHiEMOM. Check for new driver files in the repos of atmos_drivers and FV3.

Please check all whether they apply or not

[x] My code follows the style guidelines of this project
[x] I have performed a self-review of my own code
[x] I have commented my code, particularly in hard-to-understand areas
[ ] I have made corresponding changes to the documentation
[x] My changes generate no new warnings
[ ] Any dependent changes have been merged and published in downstream modules

NOAA-GFDL / SHiELD_build

Build SHiELD with the full FMSCoupler and SHiEMOM (SHIELD+MOM6) #40