[feature] Embedded Custom Workflow Builder

As a Developer
I want to be able to build and embed a custom workflow builder
So that I can build a simplified version of the workflow builder when full functionality of the platform's builder is not required

Technical Details:
- Provide all necessary public APIs required to build a custom workflow builder:
- API endpoints to list connections and to connect to a particular action with a chosen connection are missing.
- API endpoints to list, create, update, and delete workflows.
- It would be good to have an endpoint for the list of properties for a particular action/trigger.

Start by locating the public API entry points for connections, actions or triggers, and workflows; the issue names no specific files or tests. Done means the listed connection and workflow operations are exposed, with an endpoint for action or trigger properties if that remains in scope.

Written by the indexing model from the issue text.