Get participants for a group conversation only

Retrieves the list of participants for a group conversation ONLY (conversationType='groupchat') with offset-based pagination. Direct conversations already include participant information in the /v1/conversations endpoint's participants array (exactly 2 participants: senderId and recipientId). This endpoint is specifically designed for group conversations that can have many participants requiring pagination. Authorization: Requires PRO feature level. Retrieve paginated list of group participants.