Facade for the configured storage backend.
All blob storage access goes through this module — call sites should
use upload/3, download/1, etc. rather than looking up the backend
and dispatching manually.
Implement Attached.StorageBackends.Behaviour to add a new backend
and set config :attached, :storage_backend, MyBackend. Ships with
Attached.StorageBackends.Disk for local filesystem storage.
Summary
Functions
Returns the configured storage backend module.