Ensure compatability with the official MEDS schema and with the current MEDS ETL in terms of capability

[mmcdermott]

MEDS Schema: https://github.com/Medical-Event-Data-Standard/meds

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[mmcdermott]

@EthanSteinberg my plan with this is to basically make this code realize the same capabilities and conventions we have in the other ETL, as I think this base format is more naturally and easily extensible to other datasets. Basically, I've realized the structure https://github.com/Medical-Event-Data-Standard/meds_etl/blob/main/src/meds_etl/mimic/__init__.py#L63 in a config file format which I think is more portable to new datasets.