Increase password requirements

With Open edX Hawthorn we have the option to increase the password requirements from the "minimum 2 characters" default we have in place now: https://edx.readthedocs.io/projects/edx-installing-configuring-and-running/en/latest/configuration/password.html (this is Open edX documentation but since those are variables I think this is just question of creating a Tutor plugin.

Note that this was GHT-006 in the 2020 ROS audit.