FIX: Do not reload post if raw is present (PR #13335)

Editing a post that was just posted caused it to be reloaded and made a request to the server. This had an additional side effect where the model instances used by post stream and composer would be different and changes did not propagate correctly.

This is a bigger change because I also removed the useless ‘composer’ alias. Unfortunately, writing a test is a challenge because it relies on many other components.