Unblock the contact when sending a 1:1 message to it

- Operating System (Linux/Mac/Windows/iOS/Android): Windows
- Delta Chat Version: 1.51.0
- Expected behavior: 3 options:
- "Reply Privately" is not available (not the best, because it's not clear why)
- After clicking "Reply Privately", the composer is disabled, and a button "unblock contact" is displayed.
- You can send a message, but the contact gets unblocked.
- Actual behavior: You can send the message, but it's not obvious that the other party cannot reply to it. Moreover, the chat gets un-hidden from the chat list (it gets hidden after you block the contact, and AFAIK it's only supposed to be accessible through "Blocked Contacts" in settings).
- Steps to reproduce the problem:
1. Create a group with Bob.
2. Wait for Bob to send a message to the group.
3. Block Bob.
4. Open the group, right-click the bob's message, press "Reply Privately".
5. Type and send the message.
- Screenshots:
- Logs:

There was this somewhat similar MR: https://github.com/deltachat/deltachat-core-rust/pull/3218, but it goes the other way, i.e. if Bob blocks you.