Improving events regarding changing group memberships

[Anderen2]

Is your feature request related to a problem? Please describe.
When a user is added or removed to a group, it generates a single event in the event-log which appears in the affected Group's changelog only. This event only refers to the user in question by ID.

Describe the solution you'd like
The event should appear both on the affected User and the affected Group. The "Changes made" should include the username of the user, and not just the ID.

Describe alternatives you've considered
N/A

Additional context
N/A