Added file upload progress to the UI. Multiple upload progress bars are supported. Also, clicking on a file now previews the selected file. Video and images are supported.

Added real file uploading via axios, and now list actual File objects, and load project details when loading the editor. Made components conditional based on when the editor loads project data.

Removed fetch and replaced with axios (mostly due to simpler syntax, and support for upload progress events). Also added support for custom errors, for failed API calls, failed login, etc... Errors are stateful, and can be dismissed by the user.