feat: ring individual members + updates

[sachaarbonel]

The Ring Individual Members feature enables applications to ring call participants individually or in groups, rather than all at once. This implementation uses the GET call endpoint with specific member IDs to create a more natural calling experience similar to making individual phone calls to conference participants.

The feature allows developers to:

• Ring specific members of a call, one at a time or in groups
• Send targeted notifications to specific members
• Create sophisticated call flow patterns