Change syntax for routes with filename

Previously, the filename was URL-encoded, thus each / was replaced with %2F. This caused issues with some Apache2 configuration, smartly mingling with the URL to either encode it a second time (resulting in %252F) or decoding it (generating a real /). However, for authenticated file downloads with the JWT, we hardly require a byte-by-byte matching. With these changes, the URL parameter is no longer URL-encoded, so that Apache2 won't break our implementation any longer.

Further, we use this opportunity to get rid of the unnecessary .json extension for those filename routes, simplifying the routes generated and doing some further cleanup.

app/controllers/live_streams_controller.rb

@@ -22,7 +22,7 @@ class LiveStreamsController < ApplicationController
 
   def download_arbitrary_file
     @execution_environment = authorize ExecutionEnvironment.find(params[:id])
-    desired_file = params[:filename].to_s
+    desired_file = "/#{params[:filename]}" # The filename given is absolute; this is an admin-only action.
     runner = Runner.for(current_user, @execution_environment)
     fallback_location = shell_execution_environment_path(@execution_environment)
     privileged = params[:sudo] || @execution_environment.privileged_execution?