Implement UX flow and consolidate UI for MVC 1

To make the plugin easy and a joy to use, we need to implement and refine a "proper" user experience.

This issue should capture any discussion that needs to be had around what this looks like, as well as the implementation work

TODOS

  • Decide on what screens (login, upload, success or error pages?)
  • Decide on fonts, colors etc. (do we stick with GitLab UI)
  • Message copy throughout
  • Size of the plugin window

... etc

Edited by Tom Quirk