Fix handle allocator (#8970)

Use the right type for the index to prevent the value from being
truncated.

filament/backend/include/private/backend/HandleAllocator.h

@@ -204,7 +204,7 @@ public:
         } else {
             // check for heap handle use-after-free
             if (UTILS_UNLIKELY(!mUseAfterFreeCheckDisabled)) {
-                uint8_t const index = (handle.getId() & HANDLE_INDEX_MASK);
+                HandleBase::HandleId const index = (handle.getId() & HANDLE_INDEX_MASK);
                 // if we've already handed out this handle index before, it's definitely a
                 // use-after-free, otherwise it's probably just a corrupted handle
                 if (index < mId) {