IPFS file service

[Zweibach]

My idea is that when you add ipfs as a service you either get a special ipfs file service, or get to designate an existing one as the ipfs file service.

When a file is added to the file service it is automatically pinned as per #257. When the file is deleted from the file service it gets unpinned as per #517. Together with the new tracking for when a file is added to a service you could also (mostly) track their pin time as per #514.

While file migration is a planned feature as listed here something like export folders but for adding/removing files to/from a file service would also solve #426.

Suika:

Tho, I must note. The pin and unpin happen only as "commit" jobs. So if you want to really "move" the files, the auto-commit must happen or at least in the workflow of the file migration. As mentioned, ipfs is an external service and needs to have the job be committed for it to have an effect. So the migration job needs to consider this or #258 is to be implemented.