Pan strips out reply/edit metadata

[Half-Shot]

This is because m.relates_to is inside content, but not part of the ciphertext. E.g.

This is an example of a edit event sent from Element:

{
  "type": "m.room.encrypted",
  "sender": "@will:beefy",
  "content": {
    "algorithm": "m.megolm.v1.aes-sha2",
    "sender_key": "4tnx7225op7yzAfKxNBAJ9bJGvms0jLzEoVeunmpHA0",
    "ciphertext": "AwgHErABBUryOinjWfNqyrJy/P3Zbm+8nfFdCEeJVNCtdlfhdeeA1hhrHDN5N+/teE2PfLtm9iqSg2iEhkZu5rEOKKurwAgJiH5QsMBz0BOmVlle/tSmqbSA9S7JJM1xkCW9hIMoXppenJWAhIVDM6WPQi3kcwqZlxCTv2KcR61mYcTlX/We+206wLR6Rw9M4gY51M4VtWmMQaCTO23NoIxzParSGeS5a4MIfBwczv+PtOll/fnJzsGesZIOe9ZmdC5AHV7iy3cf62p6RhODTZaYWLqR4rdk6+BN/R7SAzgG8GyZCSXTaK95oGNeC3GGiIshlCColT4HhCYKSQA",
    "session_id": "Q7cwgfuBo2gwarsGHNSx484S50K6CKtSAb53qp3FOmQ",
    "device_id": "OVLSFSUAGP",
    "m.relates_to": {
      "rel_type": "m.replace",
      "event_id": "$i4Lghwml7imA5Ir7EY0Eln8Zt4i6fqZifiLlP5Pz2Vs"
    }
  },
  "origin_server_ts": 1603975928937,
  "unsigned": {
    "age": 26,
    "transaction_id": "m1603975928883.9"
  },
  "event_id": "$62WOwQXE2pCn68ZLA4o6pKZWnoBjniknXyoQNtbblTQ",
  "room_id": "!cDbbaoQeSQwVmvDGoQ:beefy"
}

This is how it arrives from pan:

{
  "type": "m.room.message",
  "sender": "@will:beefy",
  "content": {
    "m.new_content": {
      "msgtype": "m.text",
      "body": "foobar"
    },
    "msgtype": "m.text",
    "body": " * foobar"
  },
  "origin_server_ts": 1603976249057,
  "unsigned": {
    "age": 23
  },
  "event_id": "$62WOwQXE2pCn68ZLA4o6pKZWnoBjniknXyoQNtbblTQ",
  "room_id": "!cDbbaoQeSQwVmvDGoQ:beefy",
  "decrypted": true,
  "verified": false
}

[tulir]

We should just put relations inside ciphertext too (matrix-org/matrix-spec-proposals#2674 (comment))