CMEPS needs to use imported ocean fraction from FV3 to properly normalize fluxes

[DeniseWorthen]

When FV3 exports the open ocean fraction it used in actually calculating the fluxes being exported, CMEPS needs to use this value to normalize those fluxes when mapping to other components.

Related FV3 issue #230

[DeniseWorthen]

The required FV3atm export field was added in ufs-weather-model PR #475

[DeniseWorthen]

Implementing this feature requires the addition of another conservative mapping type for atm:ocean mapping. This is required because the desired normalization for some fields will be the open-water fraction returned from ATM while other fields will not have this normalization applied. Since only a single normalization type is allowed for any mapping n1:n2:maptype, a second conservative mapping must be created to allow a second packed field bundle to be created and used with the open-water normalization. See related issue #40