Ensure well_known controllers use WEB_DOMAIN by including RoutingHelper (#2388)

This fixes #2375.

app/controllers/well_known/host_meta_controller.rb

@@ -2,6 +2,8 @@
 
 module WellKnown
   class HostMetaController < ApplicationController
+    include RoutingHelper
+
     def show
       @webfinger_template = "#{webfinger_url}?resource={uri}"
 

app/controllers/well_known/webfinger_controller.rb

@@ -2,6 +2,8 @@
 
 module WellKnown
   class WebfingerController < ApplicationController
+    include RoutingHelper
+
     def show
       @account = Account.find_local!(username_from_resource)
       @canonical_account_uri = @account.to_webfinger_s