Update ocean diagnostic requests

[blimlim]

For the released configurations, we want to include new default diagnostic requests for the ocean which prevent unused variables being output. We also want to switch to saving one variable per output file to make model evaluation simpler. This will involve:

• Decide on which variables to keep, hopefully with community input (see forum post).
• Use the make_diag_table.py script used by OM2 to produce a diag table for the updated outputs, with one variable being saved per file.

[blimlim]

Closing this as updates and discussion were moved to #53 and #54.