fix: broken link in admin account user list (#11661)

- Add a dummy link for account users page that redirect back to user
page
- move common account user form in user and account super admin pages to
a partial

fixes:  #10757

config/routes.rb

@@ -533,7 +533,7 @@ Rails.application.routes.draw do
       end
 
       # resources that doesn't appear in primary navigation in super admin
-      resources :account_users, only: [:new, :create, :destroy]
+      resources :account_users, only: [:new, :create, :show, :destroy]
     end
     authenticated :super_admin do
       mount Sidekiq::Web => '/monitoring/sidekiq'