feat: key-contacts

This change introduces a new type of contacts
identified by their public key fingerprint
rather than an e-mail address.

Encrypted chats now stay encrypted
and unencrypted chats stay unencrypted.
For example, 1:1 chats with key-contacts
are encrypted and 1:1 chats with address-contacts
are unencrypted.
Groups that have a group ID are encrypted
and can only contain key-contacts
while groups that don't have a group ID ("adhoc groups")
are unencrypted and can only contain address-contacts.

JSON-RPC API `reset_contact_encryption` is removed.
Python API `Contact.reset_encryption` is removed.
"Group tracking plugin" in legacy Python API was removed because it
relied on parsing email addresses from system messages with regexps.

Co-authored-by: Hocuri <hocuri@gmx.de>
Co-authored-by: iequidoo <dgreshilov@gmail.com>
Co-authored-by: B. Petersen <r10s@b44t.com>

deltachat-rpc-client/src/deltachat_rpc_client/contact.py

@@ -37,10 +37,6 @@ class Contact:
         """Delete contact."""
         self._rpc.delete_contact(self.account.id, self.id)
 
-    def reset_encryption(self) -> None:
-        """Reset contact encryption."""
-        self._rpc.reset_contact_encryption(self.account.id, self.id)
-
     def set_name(self, name: str) -> None:
         """Change the name of this contact."""
         self._rpc.change_contact_name(self.account.id, self.id, name)