Add other Nextcloud apps to settings as suggestions

[mpivchev]

iOS Files:

• in settings: above "Transfers" with gap: Talk, Notes, "more apps"
• use same "more" icon as Desktop
• opens app if installed, if not open link to AppStore
• "more" -> open Appstore with filter for "Nextcloud"
• with multi account: open another app with correct account

Originally posted by @tobiasKaminsky in nextcloud/files-clients#10 (comment)

Update:

• When opening another app from the Files app we should switch to the same account in the other app. This should only happen if that account is logged in the other app, otherwise we just open the app as if opening it from the app drawer.
• Notes app does not have multi-account support, or a deeplink URL. Add multi account support and scheme URL for switching accounts notes-ios#40
• Talk app has no deeplink URL for switching accounts when opening app. Add scheme URL for switching accounts talk-ios#1286
• Files app for now has implemented switching apps, but without account switching: Add new section in settings for Nextcloud apps #2461

Until the above are finished, we will just open the apps as if opening them from the file drawer. No account switching or other functionality.