Add job that runs every half an hour to delete unneeded files #63
Description
If the server gets restarted / shutdown during a file action is in progress or if the client/server aborts the request for whatever reason the related files can get deleted. Over time this can lead to the server's drive becoming full and discord-cloud-storage and/or the server will stop working due to lack of storage space.
Adding a job that runs every so often to delete unneeded files will resolve this issue and prevent the server maintainer from going in and deleting zombie files every so often.
A check will need to be added to only delete files that are truly unneeded (as in not being used by a file action) because otherwise the job will delete files that are needed. The server will need to make note of what files are being in use so the job can delete any files that aren't in use.