Use Drupal's file upload capabilities

[dannylamb]

Between core REST file uploads, JSON:API file uploads, and modules such as file_upload_options, we can completely drop our custom REST endpoints. This functionality didn't exist when the project started, but it does now and we should take advantage of it.

We would be able to eliminate the MediaSourceController and most of the MediaSourceService, and whatever's remaining could probably just get rolled into IslandoraUtils.

We would have to rework what gets pumped onto the queues and islandora-connector-derivative to utilize the new methods of uploading files.

[dannylamb]

@mjordan @seth-shaw-unlv Workbench would also be affected

[mjordan]

Shouldn't be too bad, other than changing the endpoint URLs, I would imagine. I agree that getting rid of our custom enpoints is a good idea.

[ajstanley]

That is going to affect the multifile module as well - I've got a custom endpoint to attach files to existing media, and another endpoint for extracted text to both attach the file and stick the contents in an editable field.