Join FIM datasets and Limit Fields for Public Service

[CoreyKrewson-NOAA]

After implementing #345, we can add a new map for public and internal services. For the public version, we should make a new postprocess sql file that joins the various FIM datasets (HAND, SCHISM, and HEC-RAS) and reduces the fields to only a few that matter. Fields could include

• FIM Type
• Streamflow
• Reference Time
• Update Time

[CoreyKrewson-NOAA]

partially taken care of in #440, we need to wait for hecras implementation to fully do this