sql.py: DbConn.run_query(): Removed no longer used params parameter

sql.py: DbConn._db(): Setting search_path: Use esc_value() instead of params

sql.py: run_query(): Removed no longer used params parameter

sql.py: run_query_into(): Moved main case (into != None) outside of if statement because the special-case if statement contains `return`

sql.py: run_query_into(): Removed no longer used params parameter

sql.py: mk_insert_select(): Removed no longer used params parameter

sql.py: mk_insert_select(): Return just the query instead of the query plus empty params

sql.py: mk_select(): Return just the query instead of the query plus empty params

sql.py: tables(): Use select() instead of a custom run_query() to avoid using params, which will be deprecated to make it easier to support old versions of Python

sql.py: DbConn.DbCursor.execute(): Require that params are empty, to ensure that code uses db.esc_value() instead. This keeps literal values in the same place as the rest of the query, so that they do not need to be maintained and passed around separately in a params list.