The default widgets only implement the settings for the `default` "app_name"
The game specific widgets sub-class the default widgets and implement
whatever they additionally need locally.
Remove multiple calls to save config and save when the game settings gets hidden.
Because there are two dialogs for editing optional downloads, refactor
the separate implementations to select them into a common reusable widget
and use it in SelectiveDialog and InstallDialog.
The factories are also usable in Rare's code to create compatible
functions for the callbacks. If they there is no callback they just
log what is happening. It also removes the need for `typing-extentions`
module.
