imgui/renderer: Hide Cursor on Idle Implementation (#1266)

Implement hide cursor on idle w/ idle timeout duration (configurable via GUI). While at it add always and never to hide the cursor options as well.

* Revert commit #1211 as to not interfere with the cursor states.
* Make hide cursor on idle as the default setting w/ timeout duration of 5 seconds to hide.
* Add an input tab in the settings page to add the hide cursor setting, with hiding the idle timeout box with respect to the cursor hide option.

Co-authored-by: georgemoralis <giorgosmrls@gmail.com>

src/qt_gui/settings_dialog.h

@@ -33,6 +33,7 @@ private:
     void LoadValuesFromConfig();
     void InitializeEmulatorLanguages();
     void OnLanguageChanged(int index);
+    void OnCursorStateChanged(s16 index);
 
     std::unique_ptr<Ui::SettingsDialog> ui;