Add and use isForeignKeyException, fix isDuplicateException

Add and use isForeignKeyException, fix isDuplicateException

PostgreSQL exception codes are different, while mysql are the same, but
we have distinct coees in errInfo[1] entry.

see:
- https://www.postgresql.org/docs/current/errcodes-appendix.html
- https://dev.mysql.com/doc/mysql-errors/8.0/en/server-error-reference.html

Add test on members removal