Delay when interacting with posts & comments

[TheNightmanCodeth]

While this is technically a bug with Lemmy itself, a delay in the UI reflecting a change is my problem for sure.

The UI is updated when the interaction first takes place, but after a subsequent fetch from the server the change is no longer reflected. This is because sometimes the "change" (upvote, downvote, comment, favorite) can take a few seconds to register on the backend. We can keep these values stored in memory so the UI reflects appropriately the action a user took.