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/tests/test_something.py

@@ -170,7 +170,7 @@ def test_account(acfactory) -> None:
     assert alice.get_size()
     assert alice.is_configured()
     assert not alice.get_avatar()
-    assert alice.get_contact_by_addr(bob_addr) == alice_contact_bob
+    assert alice.get_contact_by_addr(bob_addr) is None  # There is no address-contact, only key-contact
     assert alice.get_contacts()
     assert alice.get_contacts(snapshot=True)
     assert alice.self_contact
@@ -287,7 +287,6 @@ def test_contact(acfactory) -> None:
     assert repr(alice_contact_bob)
     alice_contact_bob.block()
     alice_contact_bob.unblock()
-    alice_contact_bob.reset_encryption()
     alice_contact_bob.set_name("new name")
     alice_contact_bob.get_encryption_info()
     snapshot = alice_contact_bob.get_snapshot()