Upload File Page - does not handle duplicate files correctly

[ekraffmiller]

What steps does it take to reproduce the issue?
Upload a file to a dataset, and then within the same Upload form, try to upload the file again. The UI should present a warning that the file is a duplicate, then if the user allows the upload, then the second file should be renamed. For example -
JSF Duplicate File Upload

• When does this issue occur?
  Uploading a duplicate file to a dataset

• Which page(s) does it occur on?
  Upload Files Page

• What happens?
  The second upload fails silently, and doesn't get added to the form.

• To whom does it occur (all users, curators, superusers)?
  all users

• What did you expect to happen?
  The page should behave the same as the JSF.

Which version of Dataverse Frontend are you using?

Any related open or closed issues to this bug report?
#581

Screenshots:
Upload Dataset form with duplicate files, in JSF-

[ekraffmiller]

Note that there is work being done to address this in #478