[3.x] Add support for prompting the user to retain app data on uninstall.

[m4gr3d]

As specified in the documentation:

When the user uninstalls an app, whether or not to show the user a prompt to keep the app's data. 

Supported on Android 10 and higher.

[akien-mga]

Thanks!

[akien-mga]

Holding off 3.3 cherry-pick for now as the previous changes to this code (allowBackup, isGame) haven't been cherry-picked either. If we want them in 3.3.3 we should likely make a dedicated PR with all three and proper testing (I did a lot of mistakes when cherry-picking the isGame code initially for 3.x).

[m4gr3d]

There are features rather than bug fixes, so we can omit them from the 3.3 cherry-pick.