Update DOAS mini split HP measure to use new standards heat exchanger methods

[eringold]

The temporary fix here should be re-done when new HX create/modify methods are available in openstudio-standards, to something like:

new_hr = OpenstudioStandards::HVAC::create_hx_air_to_air_sensible_and_latent(model, 
                                                                             name: "#{air_loop_hvac.name} ERV",
                                                                             ...
                                                                             latent_heating_100_eff: 0.0,
                                                                             latent_heating_75_eff: 0.0,
                                                                             etc.

This is just a reminder to do that when it's available, after the release.