Improve Teaser Safety screen

[yunikkk]

Currently Safety screen displays collision warnings with the rest of cars.
But such collision warnings are not very common, so users often get confused what is actually supposed to happen on on this screen.
It would be nice to add some legend with description of mode.
Another improvement might be adding views that allow to customize safety - e.g. change thresholds for collisions, change collision types (car, pedestrian).
cc @chezzdev