qt_web_browser: Fix button inputs with QtWebEngine

Button inputs were broken as button was assumed to be the bit position of NpadButton prior to the input rewrite. Since this was changed to use NpadButton directly, we should count the number of trailing zeros to determine the bit position.

src/yuzu/applets/qt_web_browser.cpp

@@ -2,6 +2,8 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #ifdef YUZU_USE_QT_WEB_ENGINE
+#include <bit>
+
 #include <QApplication>
 #include <QKeyEvent>
 
@@ -211,8 +213,10 @@ template <Core::HID::NpadButton... T>
 void QtNXWebEngineView::HandleWindowFooterButtonPressedOnce() {
     const auto f = [this](Core::HID::NpadButton button) {
         if (input_interpreter->IsButtonPressedOnce(button)) {
+            const auto button_index = std::countr_zero(static_cast<u64>(button));
+
             page()->runJavaScript(
-                QStringLiteral("yuzu_key_callbacks[%1] == null;").arg(static_cast<u8>(button)),
+                QStringLiteral("yuzu_key_callbacks[%1] == null;").arg(button_index),
                 [this, button](const QVariant& variant) {
                     if (variant.toBool()) {
                         switch (button) {
@@ -236,7 +240,7 @@ void QtNXWebEngineView::HandleWindowFooterButtonPressedOnce() {
 
             page()->runJavaScript(
                 QStringLiteral("if (yuzu_key_callbacks[%1] != null) { yuzu_key_callbacks[%1](); }")
-                    .arg(static_cast<u8>(button)));
+                    .arg(button_index));
         }
     };