Allow restore after device set-up

[grote]

• [ ] potentially pre-uncheck system apps and settings
• [ ] run in a foreground service in case user navigates away #203
• [ ] in first fresh app start, ask if user wants to restore old backup or start fresh #571
• [ ] installing of apps should only happen if not already installed (or on older version)
• [ ] handle auto-restore setting (maybe temp disable?)
• [ ] enable restore menu item out of dev builds
• [ ] remove dialer code (from code and FAQ)
• [ ] don't create duplicate files for storage/files restore