Add button to close unavailable packages in the scenario manager. Add hint in log if that is relevant

TODO: scenarios which are prefixed (i.e. some scenarios in RobotAPI are prefixed with tests/) are not saved as
open scenarios because the prefix is dropped in the config. Therefore these do not get loaded on startup

Changed Layout of Open buttons in SettingsView + OpenScenarioView, Fixed Typos, Added Package adding Button to OpenSceanrioView

Change all icons to also be provided via static functions (GetWidgetIcon/GetWidgetCategoryIcon)