howdy/storage/memory
Storage kept in one process, for tests. Everything is lost when the process stops, and other nodes do not see it.
let files = memory.new()
let assert Ok(Nil) =
storage.put(files, "a.txt", <<"hi">>, content_type: "text/plain")
Signed URLs and direct upload URLs are memory: followed by the key,
which no browser can open; they let tests check that a URL was asked
for. Store what a browser would have uploaded with storage.put.