Mark older messages as noticed when message is marked as read via flag synchronization

[link2xt]

Currently we mark old messages as noticed when outgoing message is sent, should do the same if on another device we read some message.

We should not however just call mark_old_messages_as_noticed because it starts ephemeral timers for all messages in the chat. It should be modified to start the timer only for messages that are older than the one that is read.

We should also not send a MsgsNoticed event, because otherwise, at least Android would remove all notifications for this chat. "Chatlist item changed" should be sent.