Log audit events to a Python logger as well as to the db-backed audit log

[lunkwill42]

Is your feature request related to a problem? Please describe.

NAV audit logs various events initiated by operators to its internal audit log table in PostgreSQL. This record is closed off to NAV, and can only be inspected through the NAV web UI.

Describe the solution you'd like

All events logged to NAV's audit log should also be logged to a specific Python logger, so that this log output can also be directed to an on-disk file. This enables a site admin to ingest the log into a central logging system, if so desired.

Additional context

This wish was expressed by NTNU at a NAV reference committee meeting.