deleteMessage method
Implementation
Future<QMessage> deleteMessage(String messageUniqueId) async {
var qiscus = await ref.read(qiscusProvider.future);
var messages = state.firstWhere((v) => v.uniqueId == messageUniqueId);
await qiscus.deleteMessages(messageUniqueIds: [messageUniqueId]);
state = state.where((v) => v.uniqueId != messageUniqueId).toList();
return messages;
}