Reduce each (Accel & Fallback) to 3 options: Off, Fast, Good. Fast AA
in accelerated canvas uses SMAA with tweaks suggested by David Beinder.
Good AA is super-sampled x2.
Cairo is similarly reduced to Off, Fast, Good, which map to the Cairo
options themselves. Best is removed as it mostly affects text rendering
and not line drawing (as our text is)
Fixes https://gitlab.com/kicad/code/kicad/-/issues/8522
Conservative makes SMAA usable in Eeschema through weaker AA.
Aggressive reduces some artifacts compared to the High preset.
Restores the unused Ultra preset in the shader source to its original state.
Seth Hillbrand
david-beinder
Maciej Suminski
decimad