[Dev UI] Build a Media Upload "Manager"

[MichaelDoyle]

We need to support multi-media uploads for the prompt and flow runners, but neither have a "canvas" style input like the model runner does. In the case of the prompt runner, we primarily expect that media will be provided as input parameters to the template. Similarly, we need to support media input parameters for flows as well.

Imagine an "upload" component where multiple files of different media types can be uploaded. Previews are displayed in a carousel. Each file has a referenceId that can be referred to/bound to input parameters.

• TBD - where/how should the uploads be stored.
• Needs UX support