Bug 1680955 - Update FallbackGamepad to use new GamepadHandle type r=handyman

Starting with one of my earlier patches in Bug 1657404, FreeBSD started seeing
an error,

```
ld.lld: error: undefined hidden symbol:
  mozilla::dom::SetGamepadLightIndicatorColor
```

We don't build this codepath as part of our regular Firefox testing, and so I
didn't see the issue.

Luckily, Jan Beich <jbeich@FreeBSD.org> noticed the issue and offered up this
patch. They unfortunately can't be given credit because they are protesting
our requirement for 2FA in Phabricator.

Differential Revision: https://phabricator.services.mozilla.com/D98973

dom/gamepad/fallback/FallbackGamepad.cpp

@@ -5,6 +5,7 @@
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include <stdint.h>
+#include "mozilla/dom/GamepadHandle.h"
 
 namespace mozilla {
 namespace dom {
@@ -13,7 +14,7 @@ void StartGamepadMonitoring() {}
 
 void StopGamepadMonitoring() {}
 
-void SetGamepadLightIndicatorColor(const Tainted<uint32_t>&,
+void SetGamepadLightIndicatorColor(const Tainted<GamepadHandle>&,
                                    const Tainted<uint32_t>&,
                                    const Tainted<uint8_t>&,
                                    const Tainted<uint8_t>&,