Use file MIME type to determine whether to prompt for media alternative content

[tdonohue]

Describe the bug

Related to #3807, as this improvement came up in discussion of that ticket in a Developers Meeting.

In #3807, we've suggested creating a "type of media" field in the submission form which users can use to select the type of media file they are uploading (audio-only, video-only, audio+video). This "type of media" can then be used to prompt the user for necessary alternative media files/text (e.g. transcript, audio description, text alternative).

Ideally, we should be able to remove the "type of media" (or default it to a specific value) by analyzing the MIME type of the uploaded file. However, at this time, DSpace determines the MIME type via the file extension, which is not a reliable way to determine MIME type (e.g. ".mp4" is usually a video file, but can also be audio file).

Expected behavior

If DSpace is able to more reliably determine the MIME type, then we would be able to lessen or remove the requirement to set a "type of media" value on any uploaded media files.

Related work

#3807

[tdonohue]

I've flagged this as "needs discussion" for now because it will require deeper anlaysis of how to better determine file MIME types in DSpace.

I suspect we may need to look at libraries or tools which can determine MIME type without relying on the file extension. This also may require updates to our Bitstream Format Registry to no longer be as reliant on file extensions as well.