Validate CISM -> ocean runoff fluxes for nuopc/cmeps #70

Looking back through my notes, I don't think @mvertens and I ever validated the CISM -> ocean runoff fluxes for nuopc/cmeps. We validated the glc to lnd and lnd to glc fields, ensuring that they look the same with nuopc as with mct, but I don't think we ever verified that the runoff fluxes look the same in nuopc as in mct.

#69 should be done before this (and that issue is what made me think of this one).

@mvertens @whlipscomb @Katetc