Fix download route when installed with the redirect module

Problem/Motivation

This module currently doesn't work when installed alongside the redirect module. In redirect's RouteSubscriber it sets a flag for routes similar to file_encrypt's (i.e image styles and private files) called _disable_route_normalizer which seems to make sure redirect doesn't mess with the route too much. We need the same on file_encrypt's route.

Without this, redirect sends the user to /encrypt/files and strips off the file query parameter, resulting in a 403.