High contrast should not show the annular rings from other layers. Once
the ring is removed, we hide the annular when not focused on a flashed
layer
Fixes https://gitlab.com/kicad/code/kicad/issues/6896
Also removes EditToolSelectionFilter which was misused in more places
than it was used correctly. The original point of the client filter
was to move the logic to the point of use, which the
EditToolSelectionFilter sort of obviated anyway.
Fixes https://gitlab.com/kicad/code/kicad/issues/6751