Add system option to user and group

[TheREK3R]

Description

Add an option for the managed users and groups to be created as system

Issues Resolved

None

Check List

• [X] All tests pass. See TESTING.md for details.
• [X] New functionality includes testing.
• [X] New functionality has been documented in the README if applicable.

[kitchen-porter]

Released as: 8.1.0