fix: Save contact name from SecureJoin QR to authname, not to name (#6115)

3f9242a saves name from all QR codes to `name` (i.e. manually edited name), but for SecureJoin QR
codes the name should be saved to `authname` because such QR codes are generated by the
inviter. Other QR codes may be generated locally and not only by Delta Chat, so the name from them
mustn't go to `authname` and be revealed to the network or other contacts.

src/contact.rs

@@ -425,9 +425,12 @@ pub enum Origin {
     /// To: of incoming messages of unknown sender
     IncomingUnknownTo = 0x40,
 
-    /// address scanned but not verified
+    /// Address scanned but not verified.
     UnhandledQrScan = 0x80,
 
+    /// Address scanned from a SecureJoin QR code, but not verified yet.
+    UnhandledSecurejoinQrScan = 0x81,
+
     /// Reply-To: of incoming message of known sender
     /// Contacts with at least this origin value are shown in the contact list.
     IncomingReplyTo = 0x100,