New strategy is to draw the hole wall cylinder if the pad (or via)
isn't flashed on a particular layer. This is (1) more correct,
(2) keeps pads which aren't flashed on any layer from disappearing,
and (3) allows us to remove a bunch of the other special cases.
Or at least I think it does. The proof will be in the (lack of)
follow-on bug reports....
Also fixes a bug where via annular rings weren't highlighted in
high contrast mode.
Fixes https://gitlab.com/kicad/code/kicad/issues/7279
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