Makes Gamepad example able to be tested with Windows 10/11 (#8058)

* Makes sure it can be tested with Windows 10/11

Initial code had no effect with Win10/11 because BUTTON_START was not recognized.
This change makes it visible in the Windows Game Controller Testing TAB.

* Examples tests all USB gamepad APIs.

It is possible to change the selected gamepad button when pressing BOOT (long/short press).
The selected button is used as parameter to change R/L Stick and Trigger as well as the Hat.

libraries/USB/examples/Gamepad/Gamepad.ino

@@ -14,13 +14,41 @@ void setup() {
   pinMode(buttonPin, INPUT_PULLUP);
   Gamepad.begin();
   USB.begin();
+  Serial.begin(115200);
+  Serial.println("\n==================\nUSB Gamepad Testing\n==================\n");
+  Serial.println("Press BOOT Button to activate the USB gamepad.");
+  Serial.println("Longer press will change the affected button and controls.");
+  Serial.println("Shorter press/release just activates the button and controls.");
 }
 
 void loop() {
+  static uint8_t padID = 0;
+  static long lastPress = 0;
+  
   int buttonState = digitalRead(buttonPin);
-  if ((buttonState != previousButtonState) && (buttonState == LOW)) {
-    Gamepad.pressButton(BUTTON_START);
-    Gamepad.releaseButton(BUTTON_START);
+  if (buttonState != previousButtonState) {
+    if (buttonState == LOW) { // BOOT Button pressed
+      Gamepad.pressButton(padID);                    // Buttons 1 to 32
+      Gamepad.leftStick(padID << 3, padID << 3);     // X Axis, Y Axis
+      Gamepad.rightStick(-(padID << 2), padID << 2); // Z Axis, Z Rotation
+      Gamepad.leftTrigger(padID << 4);               // X Rotation
+      Gamepad.rightTrigger(-(padID << 4));           // Y Rotation
+      Gamepad.hat((padID & 0x7) + 1);                // Point of View Hat
+      log_d("Pressed PadID [%d]", padID);
+      lastPress = millis();
+    } else {
+      Gamepad.releaseButton(padID);
+      Gamepad.leftStick(0, 0);
+      Gamepad.rightStick(0, 0);
+      Gamepad.leftTrigger(0);
+      Gamepad.rightTrigger(0);
+      Gamepad.hat(HAT_CENTER);      
+      log_d("Released PadID [%d]\n", padID);
+      if (millis() - lastPress > 300) {
+        padID = (padID + 1) & 0x1F;
+        log_d("Changed padID to %d\n", padID);
+      }
+    }
   }
   previousButtonState = buttonState;
 }