1) The highest priority zone that a via/pad collides with "owns" its
connectivity state. Once set, lower priority zones cannot change it --
and in fact, if they would have connected to it are forced not to.
2) The connectivity state goes with the zone fill state, and therefore
must be saved in the file.
3) Display of remove-unconnected's pads is no longer done in GetViewLOD()
(which isn't called for selected items), and is instead done in PCB_PAINTER.
This allows us to draw the full pad in outline mode when a via/pad is
selected which would otherwise only show the hole.
4) Note that in some cases this will still generate DRC errors -- in
particular when a via nearly collides with a higher priority zone it
won't get "owned" by that zone and may therefore have insufficient
clearance if said zone concludes it's unconnected and a subsequent
(lower priority) zone connects to it (causing it to now become flashed).
Fixes https://gitlab.com/kicad/code/kicad/issues/11299
437d2c4589