Create a CFG package to better support DDL/DML in incremental Flyway scripts.

[gpaulissen]

A lot of Flyway incremental scripts have DDL/DML that is either:

1. not foolproof
2. not fast by using slow-by-slow code
3. verbose (rename SYS constraint to a real name)
4. fail when the object to be changed is locked (ORA-00054)

The idea is to create a package that:

1. allows a nested table of SQL error codes to ignore (nested table supports "member of")
2. check that SQL starts with INSERT|UPDATE|DELETE and not a PL/SQL block (can be overridden though)
3. introduce procedures for common operations like (create|rename|drop) column(s) or (create|rename|drop) constraint(s) with all the SQL error codes to ignore
4. use DDL_LOCK_TIMEOUT (e.g. alter session set ddl_lock_timeout=30) for the operation