WIP: Show uploaded design instantly upon upload

What does this MR do?

When a user uploads a design, they currently get presented with a design tile with no image in it - all they see is the filename, until the image upload is complete. This is captured in #12928 (closed).

This MR is a WIP proof of concept for designs being immediately visible upon upload

Demo

Future work

• See GIF above: there's a flash when the file has completed uploading (and the Apollo cache refreshes). One UI/UX approach to this might be to make the image opaque/b&w while it's being uploaded, to indicate something of a "disabled" state.
• Consider warning the user (via Browser API beforeunload event) before they leave the page