Added support of focus handle to sections of settings.

Telegram/SourceFiles/settings/settings_common.h

@@ -84,6 +84,8 @@ public:
 	}
 	virtual void showFinished() {
 	}
+	virtual void setInnerFocus() {
+	}
 	[[nodiscard]] virtual QPointer<Ui::RpWidget> createPinnedToTop(
 			not_null<QWidget*> parent) {
 		return nullptr;