Feature Request: Handle MegolmEvents, request keys from other sessions

Dear Developers,
thank you for this nice command line utility. I have an encrypted 1on1 Chat that I would like to archive. Verification and room login has been successful. But the events received from the server are of the type "MegolmEvent", which is not handled. Any clues? I attached a sample of the event.

`
Message received for room XXX [XXXXX:matrix.org] | sender XXXXX [XXX] | 2021-08-06 21:28:22 | Received unknown event: MegolmEvent(source={'content': {'algorithm': 'm.megolm.v1.aes-sha2', 'ciphertext': 'AwgFEqAB8Nan2sc7IyEabZkXwKLUyz/tlrPxMwoTPHz4H8SLhuS0AD/K7DPhV1RpOJ5AgB2tobrW7CKH0trE5B7QMvp/6XcpKiSyKAWGTqsvl07rlHqGOqEPUf7PlSUtDZMvch3lYQaMHQBieSDT6+gNpJ2iiBlpdBxZlmavcCkzm8SXo3pDcL7JK9kt4GXkQLp7tWn6EJVQ2PkZnDa7MoMtfbYxd/Lo08OMXu+2Hnm83KE/xiaTyVw3cdgj3/UuGn+kUN0rWgCgCKhjID0IwMf9ldSQb1llQXc68B+Kd61l6cGtwuBkI53UpW2yCQ', 'device_id': 'LTUQENZNRX', 'sender_key': 'qxXN13jOmr4MlspZbmBqUB85FzyJuDt8m32HkLEefD0', 'session_id': 'mmsUFWpFsdxerIBDfNGhXlODh1Mhfo+TOPYyulJI3Sk'}, 'origin_server_ts': 1628278102151, 'room_id': '!rFTyESTNxkAoyZLznY:matrix.org', 'sender': 'XXXXXXX', 'type': 'm.room.encrypted', 'unsigned': {'age': 248567915}, 'event_id': '$fkJHAvQj3M_tKxZJRqvvY6kwfInGfkPwoF31E7kpcRM', 'user_id': 'XXXX', 'age': 248567915}, event_id='$fkJHAvQj3M_tKxZJRqvvY6kwfInGfkPwoF31E7kpcRM', sender='XXXXXX', server_timestamp=1628278102151, decrypted=False, verified=False, sender_key='qxXN13jOmr4MlspZbmBqUB85FzyJuDt8m32HkLEefD0', session_id='mmsUFWpFsdxerIBDfNGhXlODh1Mhfo+TOPYyulJI3Sk', transaction_id=None, device_id='LTUQENZNRX', ciphertext='AwgFEqAB8Nan2sc7IyEabZkXwKLUyz/tlrPxMwoTPHz4H8SLhuS0AD/K7DPhV1RpOJ5AgB2tobrW7CKH0trE5B7QMvp/6XcpKiSyKAWGTqsvl07rlHqGOqEPUf7PlSUtDZMvch3lYQaMHQBieSDT6+gNpJ2iiBlpdBxZlmavcCkzm8SXo3pDcL7JK9kt4GXkQLp7tWn6EJVQ2PkZnDa7MoMtfbYxd/Lo08OMXu+2Hnm83KE/xiaTyVw3cdgj3/UuGn+kUN0rWgCgCKhjID0IwMf9ldSQb1llQXc68B+Kd61l6cGtwuBkI53UpW2yCQ', algorithm='m.megolm.v1.aes-sha2', room_id='XXXX')
`

The issue is about handling MegolmEvents for decryption in a Matrix CLI client. Look at the event handling code, likely in the module that processes incoming events. Need to understand the matrix-nio library's encryption support, specifically how to request missing session keys from other devices. Check for existing decryption logic and see where MegolmEvent is not caught. Success means encrypted messages are decrypted and displayed.

Scritto dal modello di indicizzazione a partire dal testo della issue.