Admin controls for deleting documents

[joeltg]

It feels like we need some interface - at least just for us or designated admins - for deleting a document from the prior art archive.

This involves (at least?) three steps:

• deleting the document and assertion from the postgres database
• deleting the document from the elasticsearch index
• unpinning the appropriate files from the IPFS cluster
  • as of V2, the cid of each Assertion in postgres is the hash of a directory that is pinned recursively (so that none of the contents are pinned directly). This is so that IPFS handles the logic around duplicated files - if multiple orgs upload the same file, we don't want to unpin that file unless all the orgs delete it. Pinning files indirectly by pinning a containing directory achieves this.

[metasj]

We may want to separate 'hiding' from 'deleting'.

: An uploader should be able to hide files they've uploaded (delete from postgres + elastic) : Admins should be able to delete more permanently, including unpinning from IPFS and logging that it is deleted.