Warn the user when receiving E2E encrypted messages
Steps to reproduce:
- Open Fractal
- Enter a room which has E2E encryption enabled
- Quit Fractal
- Receive some messages in that room
- Open Fractal again
- Wait for Fractal to synchronize
Expected outcome: Fractal should tell me that it received some encrypted messages that it can't decrypt, and warn me that it doesn't support E2E encryption yet.
Actual outcome: Fractal doesn't show me that I received anything.