How did this even work before?

Fixes an issue where lastN event, includes in the logic local resource and detects it as removed from lastN and schedules update of large video. If we receive this event for newly joined participant and we have pinned the local video, the event triggers update of large video which displays the wrong participant, not the pinned local video.

Use member.isFocus to decide whether a given member is the focus user

Fixes lastN video change. Resulting 'Uncaught TypeError: stream.getOriginalStream is not a function', problem detected by torture (3 participants and the last one receives last-n changed event on joining and screenshot shows: it is missing one of the participants and logs contain this error).

Callstats error reporting. Ivan is going to publish another PR about earlier failures that would apply on top of this one.

This reverts commit 88fa2ae8.