add check for zero capacity district cooling and heating

[MatthewSteen]

It's common to use DistrictCooling or DistrictHeating objects with zero capacity for designs that have radiant systems that provide cooling or heating by connecting the radiant coils that don't exist in the design to a loop with zero capacity and pump power.

In these cases, the standards creates a 90.1 baseline that also uses district energy. I think this could happen in the methods below and maybe others.

• plant_loop_heating_fuels
• plant_loop_cooling_fuels

[mdahlhausen]

This was added to OpenStudio in NREL/OpenStudio#4799 and methods removed from openstudio-standards in #1582.