Allow overriding the password from the command line

We have a special database user for migrations, as the regular user doesn't have permission to make schema changes. We're not able to have that users password saved in a file, so with this we can override it from the command line.
IMO, this is OK given that even 2.2 already reached its end of maintenance 2 months ago. Anyone still using 2.0 or 2.0 does not receive security patches anymore since at least 8 months (more than that for 2.0)