[PP-1] Component input updates should only change one prop

Overview

At present when a user edits a component on a prop, we send the the whole component model back.
In a multi-user environment we should be able to have users change props independently
See https://madebyevan.com/figma/how-figmas-multiplayer-technology-works

Proposed resolution

Change UpdateModel to only update a single prop.

User interface changes