Test Submission Wizard - Upload files

Test "Files" step

See #5 (closed) for acceptance criteria, #78 (closed) and #99 (closed) for new design elements

4. Open submission in progress/start submission and click "Next >" after selecting citation
5. Upload manuscript file
   • Try replacing the manuscript file as well
6. Upload additional files
   • Try removing, uploading more, etc.

You should not be able to continue (click "Next >") unless all non-manuscript files have both a label and a type, and the checkbox is checked.

Continued in #45 (closed) (#43 (closed) previous)