Provide a clearer error message on static data loads to signal if folks are in CSV mode

[shantstepanian]

Use case:

• Teams write sql statements as "insert mytable", which does not fit the current check using "insert into"

A better error message should be given for such use cases to hint that the file format expects CSV

We also may want to feature flag this in the future to only allow .csv to be loaded as CSV for new clients