Selective Participant Notifications for Group Calls

Introduce the ability to control which group members receive call notifications when a group call is initiated.
For example, in a group of five users, the requirement is that only Users 1, 2, and 3 should receive the incoming call experience (including notifications, ringtone, and VoIP alerts) and be able to join the call. Users 4 and 5 should not receive any call-related notifications or UI prompts in the chat—no ringtone, no VoIP alert, and no push notification.