configure_dialog: Focus the button box on start

Without this, the Reset All Settings button would be selected by default

src/yuzu/configuration/configure_dialog.cpp

@@ -97,6 +97,9 @@ ConfigureDialog::ConfigureDialog(QWidget* parent, HotkeyRegistry& registry_,
 
     adjustSize();
     ui->selectorList->setCurrentRow(0);
+
+    // Selects the leftmost button on the bottom bar (Cancel as of writing)
+    ui->buttonBox->setFocus();
 }
 
 ConfigureDialog::~ConfigureDialog() = default;