Allow All Attendees to Add New Attendees to Calendar Events

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

In collaborative environments, it is often necessary for any event participant to bring in additional team members or stakeholders, without depending solely on the event organizer.
This makes coordination more efficient, especially when organizers are unavailable.
Similar permissions exist in other popular group calendar solutions and are highly valued in business settings.

Describe the solution you'd like

Any attendee of an event should have the ability (optionally or by permission) to add/invite new attendees to existing calendar events.
When a new attendee is added, all participants and the organizer should be notified (as is currently the case for organizer changes).
Ideally, this could be managed via an event-specific setting to control whether all attendees can invite, or only the organizer and selected co-organizers.

Describe alternatives you've considered

No response

Additional context

This could be an optional permission set per event or configurable as a default calendar behavior.
If feasible, provide a log/history (or notifications) of who added which attendee.

No files, tests, or entry points are named. Start by locating the existing organizer-change attendee and notification handling, then trace how event permissions are configured. Done means attendees can be granted this capability, new additions notify participants and the organizer, and the behavior is covered by tests.