Add support for PNI fields and fix fetching (encrypted groups)

[gferon]

Tested in presage which should get us started with #206 and fix #223.

This requires to be able to provide two separate store implementations to the underlying libsignal. See https://github.com/signalapp/Signal-Android/blob/b4f6177e873cfd23cbce8fdbea8b573af8faf45d/app/src/main/java/org/thoughtcrime/securesms/crypto/storage/SignalServiceAccountDataStoreImpl.java#L26 for the requirements in Signal-Android.

[gferon]

@rubdos did you investigate by any chance how one can "upgrade" an existing account and upload some PNI keypair? I don't care that much for linking, as one can simply ask to relink (without losing any data).

[rubdos]

I have not looked into the migration logic here, no. I would rather actually implement the migration. It's not because relinking is supported in-protocol, that we can do that easily in Whisperfish already 🙈

[gferon]

I have not looked into the migration logic here, no. I would rather actually implement the migration. It's not because relinking is supported in-protocol, that we can do that easily in Whisperfish already 🙈

Yes this is what I figured. I can look into the migration, i suppose you can upload a PNI private and public key, and get some UUID back.

[rubdos]

Nitpick on the docstrings for the ServiceIdType.

To what extend did you look at the migration, yet?

[gferon]

To what extend did you look at the migration, yet?

To repeat what was said on Matrix, it looks like the migration is as easy as registering pre-keys with the server for ServiceIdType::PhoneNumberIdentity. We should be able to merge this without changing existing behaviour, and it'll let me continue to experiment with presage.