Fix state event visiblity in timeline

Rework the filtering of state events in the timeline and for lastevent. This is now consistent everywhere and includes the following:
- The timeline settings are obeyed everywhere
- A new setting is added to filter all state events
- Last event obeys the timeline setting in all cases
- The roomlist will show a state event as the latest event if it's visible in the timeline
- Names are no longer hyperlinked in eventToString if plaintext is selected.

BUG: 455048\
Closes network/neochat#148

src/models/roomlistmodel.h

@@ -116,5 +116,4 @@ Q_SIGNALS:
     void notificationCountChanged();
 
     void roomAdded(NeoChatRoom *_t1);
-    void newHighlight(const QString &_t1, const QString &_t2, const QString &_t3, const QString &_t4, const QString &_t5, const QImage &_t6);
 };