rawinput: custom threshold for BAT (button-analog type) (#654)

## Link to GitHub Issue or related Pull Request, if one exists
#653 

## Description of change
By default, BAT Positive / Negative binds trigger when the stick is
tilted 10% off the center.

This needs a bit more customization since:

1. User may want to customize the center point (e.g., guitar controller
neutral position)
2. User may want to adjust the sensitivity (e.g., guitar controller tilt
angle to trigger wailing).

## Testing
WIP

src/spice2x/overlay/windows/controller_presets.h

@@ -17,6 +17,7 @@ namespace overlay::windows {
         bool invert = false;
         double debounce_up = 0.0;
         double debounce_down = 0.0;
+        int bat_threshold = 0;
         unsigned short velocity_threshold = 0;
 
         bool is_naive() const { return device_identifier.empty() && vKey != INVALID_VKEY; }
@@ -31,6 +32,7 @@ namespace overlay::windows {
             e.invert = btn.getInvert();
             e.debounce_up = btn.getDebounceUp();
             e.debounce_down = btn.getDebounceDown();
+            e.bat_threshold = btn.getBatThreshold();
             e.velocity_threshold = btn.getVelocityThreshold();
             return e;
         }