Investigate and possibly redesign duplicate file handling and messaging

Changes in Dataverse v5 that changed how Dataverse handles duplicate files included a new popup with a warning message that appears when depositors and curators upload files that have the same content, based on checksums, that are in different directories.

There's discussion about this messaging in the GitHub issue at https://github.com/IQSS/dataverse/issues/4813 and a little more discussion in the related pull request at https://github.com/IQSS/dataverse/pull/6924.

The popup lists the names of files that have the same content/checksums. And the discussion in the related GitHub issue at https://github.com/IQSS/dataverse/issues/4813 makes me think that we intended the warning in the popup to include the directory path of each duplicate file. This is mentioned in the second thing listed in the comment at https://github.com/IQSS/dataverse/issues/4813#issuecomment-637706288 and in the comment in the pull request at https://github.com/IQSS/dataverse/pull/6924#issue-622037829.

And in the GitHub issue, @steeleworthy wrote about why it was important that the messaging include where each duplicate file is located.

The GitHub issue also links to a Google Doc that might have more discussion but has since been deleted.

The section in User Guides about duplicate files mentions the warning but doesn't specify if the path of each files would be included.

But the current popup shows only the name of each file. For example, here's the popup I see when uploading a zip file on Demo Dataverse, which was running Dataverse v6.1 at the time of upload:

Was it intended that only file names, without any indication of where those files are, should be included in this popup? Or should the file paths be included, which would mean that this is partly a bug?

I'm also concerned about the formatting of the message when so many files are included, like in the screenshot above. It's difficult for me to tell what the sentence is saying since important parts of it, "have the same content as" and "that have already been uploaded", are lost in the lists of file names, and adding the file paths would make this even worse. Maybe this wasn't noticed when it was designed because the messaging was tested with fewer files?

Here's the warning message that appears when I upload a zip file that has just four files:

It might be helpful to add some text formatting or to rearrange the sentence a bit, e.g. adding emphasis to certain parts of the sentence, adding line breaks to separate both lists, or listing the files at the end of the sentence.

Lastly, even if the file paths are included, I'm concerned about how helpful the current message format has and will be for depositors, especially when there are so many duplicate files in different directories, and it would be helpful to learn from users about this.

Start by reviewing issue #4813, pull request #6924, and the User Guides section on duplicate files, then compare their discussion with the current duplicate-file popup described here. Done means reaching an agreed decision about whether paths should appear and how the message should handle many duplicates, with the intended user-facing behavior documented.