android: refactor deprecated android:allowBackup

[accumulator]

android: update p4a to ref b1b528cd8b681c0b5185ab82a319527037cc2421:

• qt6: refactor deprecated android:allowBackup and android:fullBackupContent to Android12+ android:dataExtractionRules + xml definition.
• qt6: retain android:allowBackup for android 8-11

Disallow device-transfer (nearby share, USB)

(old allowBackup="false" behaviour was only considering cloud backup)

[accumulator]

crap, removal of android:extractNativeLibs="true" snuck in..
Should not be a problem though

[SomberNight]

Disallow device-transfer (nearby share, USB)

I don't know if we want to do that. e.g. when migrating to a new phone, it might be nice to move the Lightning state and keep using the channels. I wonder if the user can still launch the app on the old phone though :/

[SomberNight]

but I think it's a good idea to opt-out of the cloud backups, which IIUC the current (deprecated?) setting does.
That is, I think device-to-device transfers we could allow, but cloud backups, maybe not.

If the currently used android:allowBackup pref is being deprecated, maybe we still need half of that new backup_rules.xml file you wrote in spesmilo/python-for-android@29b4818 ?

[accumulator]

For now the current status-quo is fine IMO, we should revisit after we have strengthened wallet KDF