Bandit: Unauthenticated one-shot DoS via `Transfer-Encoding: chunked`

Summary Bandit's HTTP/1 chunked-body reader silently drops the request size cap that the application configures e.g. Plug.Parsers' default 8 MB length: and buffers the entire body in memory before the application sees it. An unauthenticated attacker can crash any Bandit-fronted Phoenix/Plug app...