Map ECMO flowsheet rows to OMOP concept

@jchang:

It’s not in OMOP currently, and not part of the core in future, either. Those are configurations of a device. This would be an expansion of the OMOP CDM, which we welcome. But you guys have to figure out it. Good news: @funaesthesia and her friends have discussed it before: ECMO and DEVICE_EXPOSURE - #3 by funaesthesia. Come up with a good model and we endorse it.