User Metadata in the UI

[Alex-Tideman]

Is your feature request related to a problem? Please describe.

Currently the UI is driven by data provided by the server, which is technical and not easily understandable by someone new to Temporal or the workflows being run. It would be great to allow users to write their own metadata so it can be more easily understood.

Describe the solution you'd like

Provide users the ability to view summary and details metadata as a Payload on a workflow and on all events in the event history, and query for the current state of the workflow. The UI should support Markdown if provided in the metadata

Describe alternatives you've considered

Additional context