Consider adding way to control table insert order

Currently, the JSON file for a source is written with the primary table first and then the rest of the tables as fetched from `self.metadata.tables`. This appears to be sorted alphabetically.

In circumstances where object tables refer to each other, such as a CompanionRelationship table that contains entries that a CompanionParameters table points to, this causes an error as the "R" is after "P" in the table. That is, a foreign key error will occur because the CompanionRelationship table is not loaded before CompanionParameters.

This DB generally assumes that object tables will point back to either the primary table or lookup tables, not to each other. If we want to support this we may need to provide a list of the order to use.