Implement archived rooms

*This issue was originally created by [**@kegsay**](https://github.com/kegsay) at .*

Specifically this is the `include_leave` part of the filter.
Sytests:
```
× Archived rooms only contain history from before the user left
```

Start by tracing the Matrix room filter's include_leave handling and run the named Sytest. The archived-room behavior should ensure the user sees only history from before leaving, and the work is done when the “Archived rooms only contain history from before the user left” test passes.

Written by the indexing model from the issue text.