feat: treat the handle as private info

[GeopJr]

⚠️ This is a secrets version bump - you'll be asked to re-login. You can safely move back to the main branch and your old logins will work just fine. If anything happens, go to Passwords and Keys and remove all Tuba entries. ⚠️

Mostly an RFC. This PR will treat the instance account handle as private info.

The good

UUIDs will be used instead to distinguish your account outside of Tuba. That includes both the secrets and gsettings.

Benefits

• Per account settings (when done), will be under /dev/geopjr/Tuba/.../e1cb8003-044e-4353-aa72-34aa7f9714fb/ instead of /dev/geopjr/Tuba/.../mastodon_at_mastodon_dot_social/
• The last active account will also become e1cb8003-044e-4353-aa72-34aa7f9714fb instead of [at]mastodon[at]mastodon.social
• Same for the wallet login attribute
• With feat: network cleanup #616, individual caches will be possible and anonymous .cache/Tuba/e1cb8003-044e-4353-aa72-34aa7f9714fb/images/

Why

An example scenario for this threat model would be: A device belonging to an activist gets compromised, either physically (if the device is unencrypted) or remotely. The attacker can easily associate them with their online accounts from Tuba using gsettings or .cache.

Obviously there will be other ways for that info to be found but since we can prevent Tuba's impact we might as well do it.

The bad

While I've set it up in a way to generate the UUID's on existing logins without having to re-auth, it might be needed if we want to use UUIDs even on secret attributes. I need to take a deeper look into it.{1}

The change is basically this:

There's an additional downside of not recognizing the keys right away.
Changing the attributes will require a re-auth.

edit: {1}

It is recommended that attribute names are human readable, and kept simple for the sake of simplicity.
...
Services implementing this API will probably store attributes in an unencrypted manner in order to support simple and effecient lookups.
https://specifications.freedesktop.org/secret-service/latest/ch05.html

🤔

edit 2: from my understanding, gnome-keyring actually hashes the attributes which is great! This PR is probably no longer needed then