Add support for Game Recording clips

[Virkkunen]

Steam has introduced Game Recording, and you can share the clips to a chat, and view those in chat as well.

The bridge doesn't load the video, though, only sends a [video] tag with the link to the file.

Source for the message in question:

{
  "type": "m.room.message",
  "sender": "@***:***.***",
  "content": {
    "msgtype": "m.text",
    "body": "[video src=\"https://steamusercontent-a.akamaihd.net/ugc/*******/******/\" type=\"video/mp4\" steamvideo=\"true\" associated_app=\"1245620\"] https://steamusercontent-a.akamaihd.net/ugc/*******/******/ [/video]",
    "source": "steam"
  },
  "origin_server_ts": 1719658451732,
  "unsigned": {
    "age": 70
  },
  "event_id": "$VouoEOfw_JMXl_89As17u3c6RULe1Y8I6CSTEUArAwI",
  "room_id": "!UVyNQsGe*****:***.***"
}