clean up warehouse module

[bjamesvERT]

The warehouse fused data source is old & needs to be cleaned up, as well old functions that predate implementation of the warehouse module.

The old fused source is not up to feature parity with that of the other individual sources: https://www.nwfsc.noaa.gov/data/api/v1/source/warehouse/variables

[ghost]

data/data.py calls warehouse.get_sql_filtered (in module) and ends up back in data.py, needs to be separated