R1:bf83fffca129

Correct the flow of edit authority when sending messages to HarbormasterBuild objects

Summary:
Ref T13072. Currently, Harbormaster builds react to messages by applying a transaction inline (which can race) that has no real effect.

Later, the BuildEngine picks up the mesasge and applies a real effect, but this isn't transactional.

This is backwards, and makes it more difficult to transition to ModularTransaction and EditEngine. The desired workflow is:

- sending a message //just// writes to the…