Native API should support deleting files

[pdurbin]

At #3415 (comment) @raprasad and I have been talking about how user's shouldn't need to switch to the SWORD API just to delete a file. This operation should be part of the native API. Yesterday, @djbrooke said to go ahead and create an issue for this so here it is.

For reference, here's how to delete a file with SWORD: http://guides.dataverse.org/en/4.5.1/api/sword.html#delete-a-file-by-database-id

The code SWORD uses is the deleteMediaResource method here: https://github.com/IQSS/dataverse/blob/v4.5.1/src/main/java/edu/harvard/iq/dataverse/api/datadeposit/MediaResourceManagerImpl.java#L131

At http://guides.dataverse.org/en/4.5.1/api/sword.html#known-issues we document a known issue with deleting files via SWORD (SWORD: deleting a file from a published version (not a draft) creates a draft but doesn't delete the file #2464 ) and I hope that we don't end up having the same problem with the native API. Highly related to that file delete issues is #2222 which should probably be consolidated, perhaps into this issue. There's a REST Assured test at for #2464 at https://github.com/IQSS/dataverse/blob/v4.5.1/src/test/java/edu/harvard/iq/dataverse/api/SearchIT.java#L645 but unfortunately the SearchIT class is not being run at https://build.hmdc.harvard.edu:8443/job/phoenix.dataverse.org-apitest-develop/ because of database deadlock issue (PSQLException: ERROR: deadlock detected running integration tests #2460) and because SearchIT is an old class that may not run well against a remote server (i.e. sending API commands across the wire from the Jenkins server to the phoenix server).

[pdurbin]

A comment from @leeper at #3913

The native API currently allows file update (and now file replace) operations but it doesn't appear to allow file delete. This means that because replace only works on published files, it is not possible to update the file contents of a draft dataset without going through the GUI to manually delete the staged file or to delete the entire draft (all files and metadata) through the API. It would be great to be able to delete both unpublished/draft files and to delete files generally from a version (in the way that is currently possible through the GUI).

[pdurbin]

#3913 is actually better expressed from the user perspective so I'm closing this issue in favor of that one.