Implement onboarding for P3A on Android

[AlexeyBarabash]

Description

The follow up issue for #6176 . It is required to implement notification about P3A during onboarding as it is done for desktop.

Designs

For new users, show an initial welcome screen with P3A checkbox before the privacy onboarding experience:

(This has the same Brave logo animation as in the first version of onboarding.)

For new users who viewed the onboarding message p3a.enabled should be true, p3a.notice_acknowledged should be true

For existing users, show the P3A checkbox modal on next app launch:

The P3A checkbox modal takes priority over any other modals that might be in queue (for example, set Brave as default browser).

"Private product analytics" links to https://brave.com/p3a

Assets

Figma: https://www.figma.com/file/atoL4LN2kd8ILnPGwohUoV/?node-id=1511%3A24317

[karenkliu]

Designs added!

[AlexeyBarabash]

awesome, thanks @karenkliu

[deeppandya]

@karenkliu is the checkbox is clickable here ? if it is, then what should happen when user unselect the check box ?

[karenkliu]

@deeppandya The user can tap on the checkbox to unselect it. If unselected, p3a.enabled should be false, p3a.notice_acknowledged should be true

Checkbox spec is here: https://www.figma.com/file/z9wmg2FCwuXx9FLbDo5avJ/Platform-UI-Brave-desktop?node-id=105%3A244 (use Roboto for the text but try to match checkbox color and style)

[bsclifton]

@deeppandya can we close #6688 as a duplicate? This has more details

Basically, we need to cover the new user (onboarding) case - but also the case where user is already an existing user. If you want, you can edit/use #6688 to cover the existing user case

[deeppandya]

@bsclifton I think this issue has covered both scenarios. I will close the other issue

[srirambv]

Verification passed on OnePlus 6T with Android 10 running 1.20.100 x64 build

• Verified P3A onboarding is shown on a clean install
• Verified opt-in or opt-out on a clean install shows privacy stats onboarding immediately after P3A is dismissed
• Verified onboarding is shown on an upgrade profile
• Verified P3A metrics are captured based and sets value based on https://github.com/brave/brave-browser/wiki/P3A

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Verification passed on Samsung Tab A with Android 10 running 1.20.100 x64 build

• Verified P3A onboarding is shown on a clean install
• Verified opt-in or opt-out on a clean install shows privacy stats onboarding immediately after P3A is dismissed
• Verified onboarding is shown on an upgrade profile
• Verified P3A metrics are captured based and sets value based on https://github.com/brave/brave-browser/wiki/P3A

[deeppandya]

How can I change this setting again?

@newuser-web you can change it from settings-> Privacy.