Maintain a per-component set of prop expressions/sources

Overview

In DummyPropsEditForm we're reading the following from the component list data:

• sourceType
• sourceTypeSettings
• expression

However this assumes that every component uses the same expression/source. It does not allow for linked/dynamic values.

Proposed resolution

Evolve the client-side model to store these on a per-component basis. Send the component specific version in DummyPropsEditForm

User interface changes