fix(SDK): ensure oculus touch uses correct controller for button press

The Oculus controller SDK was returning the same controller type for
both button presses, meaning the left controller (or index 0) was
initiating button presses on both controllers.

This has been fixed now by also checking for the generic `Touch`
controller type and using the given index to determine which
touch controller is being used.

Assets/VRTK/SDK/Oculus/SDK_OculusController.cs

@@ -714,7 +714,7 @@ protected virtual bool IsButtonPressed(uint index, ButtonPressTypes type, OVRInp
             VRTK_TrackedController device = GetTrackedObject(GetControllerByIndex(index));
             if (device != null)
             {
-                OVRInput.Controller controllerMask = GetControllerMask(device.index);
+                OVRInput.Controller controllerMask = GetControllerMask(index);
                 switch (type)
                 {
                     case ButtonPressTypes.Press:
@@ -739,7 +739,7 @@ protected virtual bool IsButtonPressed(uint index, ButtonPressTypes type, OVRInp
             VRTK_TrackedController device = GetTrackedObject(GetControllerByIndex(index));
             if (device != null)
             {
-                OVRInput.Controller controllerMask = GetControllerMask(device.index);
+                OVRInput.Controller controllerMask = GetControllerMask(index);
                 switch (type)
                 {
                     case ButtonPressTypes.Touch:
@@ -760,6 +760,8 @@ protected virtual OVRInput.Controller GetControllerMask(uint index)
 
             switch (activeControllerType)
             {
+                case OVRInput.Controller.Touch:
+                    return (index == 0 ? OVRInput.Controller.LTouch : (index == 1 ? OVRInput.Controller.RTouch : OVRInput.Controller.None));
                 case OVRInput.Controller.LTouch:
                     return (index == 0 ? OVRInput.Controller.LTouch : OVRInput.Controller.None);
                 case OVRInput.Controller.RTouch: