jb: option to draw debug graphics to show touch interactions (#797)

## Link to GitHub Issue or related Pull Request, if one exists
related to #697 

## Description of change
Add a new option that paints touch targets and touch points for jubeat;
gets enabled if there is a touch screen connected. This is to help
explain / debug issues when users have their touch screen issues, which
is usually due to misalignment.

Fix the touch targets being off by 1 pixel (center gap is 1px wider in
both directions).

Also, simplify the `improved` algorithm to simulate a finger and trigger
nearest-neighbor for the AC dimensions. In terms of touch performance
this is near identical to what we had before, but it allows us to draw a
nice debug overlay instead of just grids.

## Testing
Tested portrait and landscape versions of jb.

src/spice2x/launcher/options.h

@@ -263,6 +263,7 @@ namespace launcher {
             IIDXWindowedSubscreenAlwaysOnTop,
             spice2x_JubeatLegacyTouch,
             JubeatTouchAlgo,
+            JubeatTouchDebug,
             spice2x_RBTouchScale,
             RBTouchSize,
             RBTouchPollRate,