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 #148 (closed)