* Add unpeek * Don't allow peeks into encrypted rooms * Fix send tests * Update consumers
Initial implementation of MSC2753, as tested by https://github.com/matrix-org/sytest/pull/944. Doesn't yet handle unpeeks, peeked EDUs, or history viz changing during a peek - these will follow. https://github.com/matrix-org/dendrite/pull/1370 has full details.