Provide option to change audit log format to use JSON

[mreynolds389]

Description

Provide option to write audit log in a json format.

See: https://www.port389.org/docs/389ds/design/audit-json-logging-design.html

[mreynolds389]

PR was merged to Main branch. It should probably be backported to other branches, but I'll wait for that decision from the lead/PO.