sendMessage method
- QChatSendMessageParam param
发送消息
Implementation
Future<NIMResult<QChatSendMessageResult>> sendMessage(
    QChatSendMessageParam param) {
  return _platform.sendMessage(param);
}发送消息
Future<NIMResult<QChatSendMessageResult>> sendMessage(
    QChatSendMessageParam param) {
  return _platform.sendMessage(param);
}