Add auditLog system
This MR only contains the framework for the new auditLog system. See the docs and test (https://gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/blob/5939b288f65c9c4fe2e6d507bad80afea166de77/lemonldap-ng-common/t/TestPsgi.pm) for examples of how it works.
I will then create a second MR to start migrating some of the existing userLogger calls to this new system
The feature is marked as beta for now