Function deltachat::chat::mark_old_messages_as_noticed

pub(crate) async fn mark_old_messages_as_noticed(
    context: &Context,
    msgs: Vec<ReceivedMsg>
) -> Result<()>

Marks messages preceding outgoing messages as noticed.

In a chat, if there is an outgoing message, it can be assumed that all previous messages were noticed. So, this function takes a Vec of messages that were just received, and for all the outgoing messages, it marks all previous messages as noticed.