Changes to Update subscriber

added the new optional request property subscriber_data/fcm_app_id

added the new optional request property subscriber_data/fcm_platform

added the new optional request property subscriber_data/fcm_token

added the optional property fcm_app_id to the response with the 200 status

added the optional property fcm_platform to the response with the 200 status

added the optional property fcm_token to the response with the 200 status