'Save for later' Feature

[tobbbles]

I'm unfortunate in that I do not have a lot of storage space, and often have to rotate through my usage of a few hundred gig, deleting series and movies as I want to add more.

I'd still love a way to be able to track what I want to download in the future, almost like a request, but it doesn't trigger any action in {Rad,Son}arr - rather it just maintains a list ready for me to re-visit in future and request, in which items would be removed from my 'Saved for later' list, and be moved into my requests.