rb: touch debug overlay, tweak scaling (#801)

## Link to GitHub Issue or related Pull Request, if one exists
n/a

## Description of change
Similar to #797, draw an overlay to debug touch issues for reflec beat.

For rb, we draw on the ImGui surface. Draw horizontal and vertical line
for triggered sensors, and also a bounding box if scaling is in use.

Make small tweaks to how scaling works.

## Testing
Verified volzza 2 / reflesia / 1st game (landscape KBR)

src/spice2x/games/rb/touch_debug.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include <atomic>
+
+namespace games::rb {
+    extern std::atomic_bool TOUCH_DEBUG_OVERLAY;
+
+    bool touch_debug_overlay_enabled();
+    void touch_draw_debug_overlay();
+
+    void touch_debug_attach();
+    void touch_debug_detach();
+    void touch_debug_publish(const unsigned char *data, bool is_landscape);
+}