fix(core,app,android): keep the password out of storage and refuse key-only 2FA

Moves to proton-sdk / proton-drive-rs 0.7.3.

The stored Proton session now holds, per account key, the passphrase derived
from the mailbox password at sign-in, and resumes through
`ProtonDriveClient::with_key_passphrases`. The mailbox password — on a
single-password account, the login password — and the key salts are no longer
stored. A session in the earlier shape, which only development builds of
1.2.0 wrote, reads as signed out: signing in again replaces it.

An account whose only second factor is a security key is refused at sign-in
with a reason, rather than asked for a code that can only fail as a wrong one.
The code prompts now say plainly that security keys are not supported.

Cargo.toml

@@ -28,8 +28,8 @@ authors = ["Nils Pukropp <contact@narl.io>"]
 opt-level = 2
 
 [workspace.dependencies]
-proton-sdk = { version = "0.7.2" }
-proton-drive-rs = { version = "0.7.2" }
+proton-sdk = { version = "0.7.3" }
+proton-drive-rs = { version = "0.7.3" }
 
 # Internal crates.
 pstr-core = { path = "crates/pstr-core" }