FIX: Restore server side route for tag messages filter.

FIX: Restore server side route for tag messages filter.

Follow-up to 016efeadf6f242e04daf5ef8e18c2ca708a1392d

diff --git a/config/routes.rb b/config/routes.rb
index 380e3b0..28cb935 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -453,6 +453,7 @@ Discourse::Application.routes.draw do
       get "#{root_path}/:username/messages/personal/:filter" => "user_actions#private_messages", constraints: { username: RouteFormat.username }
       get "#{root_path}/:username/messages/group/:group_name" => "user_actions#private_messages", constraints: { username: RouteFormat.username, group_name: RouteFormat.username }
       get "#{root_path}/:username/messages/group/:group_name/:filter" => "user_actions#private_messages", constraints: { username: RouteFormat.username, group_name: RouteFormat.username }
+      get "#{root_path}/:username/messages/tags/:tag_id" => "user_actions#private_messages", constraints: StaffConstraint.new
       get "#{root_path}/:username.json" => "users#show", constraints: { username: RouteFormat.username }, defaults: { format: :json }
       get({ "#{root_path}/:username" => "users#show", constraints: { username: RouteFormat.username } }.merge(index == 1 ? { as: 'user' } : {}))
       put "#{root_path}/:username" => "users#update", constraints: { username: RouteFormat.username }, defaults: { format: :json }

GitHub sha: bfe24f74e1450c03287374745230fea47d3c77d6

This commit appears in #13953 which was approved by martin. It was merged by tgxworld.