New internal_user API response fields

Changed

• New internal_user response field in the following Webinars API:
  • GET /v2/past_webinars/{webinarId}/participants
• New internal_user response field in the following Meetings APIs:
  • GET /v2/past_meetings/{meetingId}/participants
  • GET /v2/meetings/{meetingId}
  • GET /v2/accounts/{accountId}/meetings/{meetingId}