The disable grid hotkey should allow the snap scale to be completely
determined by the snapSize and world scale. This prevents snapRange
from overriding in the case where grid is disabled.
Additionally, we disallow grid snapping when the grid scale is not
visible. This means that when zoomed out sufficiently to not show the
minor ticks, these minor ticks will not override a snap
Fixes https://gitlab.com/kicad/code/kicad/issues/12303