[PP-1] [Needs design] Implement design treatment for fallback component

Overview

In 🐛 Cannot delete JS components due to component depending on them Active we added a fallback plugin that steps in when a component goes missing.
In that issue @lauriii asked Callum to implement a design for how to convey this to the user both in the preview and in the layers panel.

Proposed resolution

Implement the design once it is ready

User interface changes