Refer to groups by UUID

[orange-elephant]

Happy new year!

For now entries can only be added to 1 group, but basically everything needed to make adding to multiple possible is already laid down here, and I'll be happy to work on that if this PR is merged.

[alexbakker]

Awesome work as always! Unfortunately I haven't had time to look at this yet, and I may not be able to get to it in the next couple of weeks either. Sorry about that. Starting February I should have some more time for Aegis.

[alexbakker]

Apologies for the delay. I've added some initial comments. Don't be afraid to push back if you think I'm asking for something that wouldn't work well. With a large patch like this it's easy to miss details.

[orange-elephant]

I've finally gotten round to addressing the feedback, everything you suggested was okay. The only thing I'm still not sure about is how to get the "New group" button into the dropdown checkboxes so I've reverted that to the original approach for now and see if I can come up with a workaround.

It would probably be possible to migrate entries that claim to be in a group that has been discarded due to duplicate names to the UUID of the group of the same name which was kept but this would be a super rare circumstance and the user could easily add them back to the group so I'm not sure if that would be worth it, what do you think?

[alexbakker]

Finally had some time to look at this again. Overall I'm pretty happy with this, but I'd like to take another look at the migration logic later this week before merging this, because I don't think I fully understand it yet. For example, I don't understand why we need to call Vault.migrateOldGroupIfNecessary(_vault, entry); in VaultRepository.addEntry(VaultEntry entry).

Also, I've made a couple of minor changes here and there, I hope you don't mind.

[orange-elephant]

why we need to call Vault.migrateOldGroupIfNecessary(_vault, entry); in VaultRepository.addEntry(VaultEntry entry).

This was because addEntry is used instead of Vault.fromJson when importing a JSON vault file (at least anytime other than the intro slides) so if the JSON backup had an old style group then this needs to be converted when it is added to the vault. This conversion may only need to happen if the entry is being added from ImportEntriesActivity since I don't think its possible for QR codes to contain info about a group.

Also, I've made a couple of minor changes here and there, I hope you don't mind.

No problem, the group model is much better than what I had

[alexbakker]

Thanks a lot!