Implement the Workflow Instances section as we have on Serverless Logic Web Tools.

This will require one additional (optional) property for the Data Index URL in the data JSON file (`dataIndexExternalUrl`).

If the data index URL property is not present or the given URL cannot be accessible, the Workflow Instances section should not be shown (or disable the section and warn the user about it).

Since the data index can be embedded in the deployment, we can also have a boolean property `embeddedDataIndex`. If true, `dataIndexExternalUrl` is ignored and we must try to fetch the embedded data index.