Put cdn.putDir logic inside OC

[ricardo-devis-agullo]

This puts the putDir logic back on OC. The reason is that

1. The logic is the same for all storage adapters (since no storage has really the concept of directories, it just does a loop of putFiles)
2. There's specific OC logic (making server.js and .env private) that doesn't belong on storage adapters, because they should be agnostic about OC and just have the simple logic of managing files on a storage.