game_list: Remove unnecessary conversion to std::string in ValidateEntry()

We can just use the file interfaces that Qt provides to prevent needing
to convert to std::string.

src/yuzu/game_list.cpp

@@ -258,18 +258,20 @@ void GameList::AddEntry(const QList<QStandardItem*>& entry_items) {
 
 void GameList::ValidateEntry(const QModelIndex& item) {
     // We don't care about the individual QStandardItem that was selected, but its row.
-    int row = item_model->itemFromIndex(item)->row();
-    QStandardItem* child_file = item_model->invisibleRootItem()->child(row, COLUMN_NAME);
-    QString file_path = child_file->data(GameListItemPath::FullPathRole).toString();
+    const int row = item_model->itemFromIndex(item)->row();
+    const QStandardItem* child_file = item_model->invisibleRootItem()->child(row, COLUMN_NAME);
+    const QString file_path = child_file->data(GameListItemPath::FullPathRole).toString();
 
     if (file_path.isEmpty())
         return;
-    std::string std_file_path(file_path.toStdString());
-    if (!FileUtil::Exists(std_file_path))
+
+    if (!QFileInfo::exists(file_path))
         return;
-    if (FileUtil::IsDirectory(std_file_path)) {
-        QDir dir(std_file_path.c_str());
-        QStringList matching_main = dir.entryList(QStringList("main"), QDir::Files);
+
+    const QFileInfo file_info{file_path};
+    if (file_info.isDir()) {
+        const QDir dir{file_path};
+        const QStringList matching_main = dir.entryList(QStringList("main"), QDir::Files);
         if (matching_main.size() == 1) {
             emit GameChosen(dir.path() + DIR_SEP + matching_main[0]);
         }