CATROID-1199 Link to flavors from settings

[friendo97]

Instead of being able to toggle the extension on and off a dialog for downloading the extension's app is shown. Depending of the extension

Remark: We expanded the SettingsFragmentTest so the this functionality can be tested, but we didn't find a way to automatically test the different flavors!

Remark: Some apps are not available in the Huawai Appgallery, so we put in the link to pocket code in those dialogs for now!

https://jira.catrob.at/browse/CATROID-1199

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[Tamdav]

Looks good to me!