This adds a --http_max_response_size argument to the serve and fetch command
which is enforced by the HTTP client. This defaults to null, no limit.
As-is, the ScriptManager allocates a buffer based on Content-Length. Without
setting this flag, a server could simply reply with Content-Length: 99999999999
9999999999 to cause an OOM. This new flag is checked both once we have the
header if there's a content-length, and when reading the body.
Also requested in https://github.com/lightpanda-io/browser/issues/415
