Onboarding experience

[Slion]

Have a preference option to display onboarding when the application starts. This preference option should also be accessible from settings. We ought to:

• Prompt the user to accept terms of use and privacy policy
• Prompt user to review crash report and analytics options - not needed for F-Droid as it has neither
• Prompt the user to grant notification permission for downloads and incognito mode

Incognito mode should redirect to splash screen if onboarding is enabled.

Consider using our AppIntro fork.

• [x] Fix bolt animation gone after config change, rotation or even just resume
• [x] F-Droid: skip telemetry onboarding
• [x] F-Droid: check terms and conditions
• [x] When terms are accepted move to the next step automatically
• [x] When notification permission is granted or denied finish the activity.
• [ ] Bug: When telemetry is the last slide background color is not set after screen rotation. Not an issue when notification permission is the last slide so possibly an AppIntro bug with custom fragment slides.
• [ ] Bug: Slion/Preference#4
• [x] Add an option to turn on Ad Blocker on a new slide I guess
• [x] Align About settings entry for terms and policy, both icons and strings
• [x] Review strings
• [x] Sort out incognito workflow
• [x] Test on various devices
• [x] Merge to main
• [x] Release