Adapt to Android 11 AOSP changes

There might be changes in Android 11 (to be released in September) that require adaption to Seedvault to run on that new version of AOSP.

Candidates are:

• Package visibility in Android 11
• Storage updates in Android 11
• changes to the platform backup API
• …?

Things to revisit:

• https://github.com/stevesoltys/seedvault/pull/113 user_full_data_backup_aware
• https://github.com/stevesoltys/seedvault/wiki/Known-Issues#apps-that-are-stopped-do-not-get-backed-up
• https://github.com/stevesoltys/seedvault/pull/98 AOSP kotlin dependency versions - check and align
• …?

[grote]

I haven’t found a way to actually use this and we would have to rename our transport to something with EncryptedLocalTransport in the class name. It all seems pretty unfinished to me and I wouldn’t trust this code with our backups. At the moment, I only see many issues, but no real benefits. But people are of course welcome to do their own deeper research than the superficial one I did. Ideally a PoC PR would come out of this as well.

[grote]

First findings from looking at early diffs of android.app.backup:

• There’s now an API to block keys in KV restore because they can cause bad UX on certain devices!? [commit] [commit] references bug 145126096
• any java library that compiles @UnsupportedAppUsage requires a direct dependency on “unsupportedappusage” java_library [commit]
• No New Data flag for Key/Value Backups to update last_updated timestamp [commit] [services commit]

Next up services.backup:

• Dedicated APK for backup encryption as a wrapper around a backup transport
  • [move to APK commit]
  • [backuplib commit]
  • [DelegatingTransport commit]
  • [BackupEncryptionService commit]
  • [route KV commit] - interesting: boolean shouldEncrypt =
  • [commit]
• replace “android” by PLATFORM_PACKAGE_NAME [commit]
• potentially skipped backup/restore of wallpaper package [commit] [secure settings change]

Others that are related:

• AOSP SystemUI can be backed up now [commit]