Farcaster reactions are delivered as properties of a message. Also, they don't say who reacted. This means we can't use the existing reaction type - we can't deterministically create a set of react and unreact messages based on a received message.
The solution to that is a new message type. For each message there is going to be at most one such a message. We can deterministically create it from the Farcaster data.
https://linear.app/comm/issue/ENG-11244/support-receiving-reactions-on-comm
Depends on D15333