Fix todo API when used with Alerts

- Add correctly named route
- Allow Todos to work with scoped models

Changelog: fixed

config/routes/project.rb

@@ -360,6 +360,10 @@ constraints(::Constraints::ProjectUrlConstrainer.new) do
           get 'details', on: :member
         end
 
+        resources :alert_management, only: [], as: 'alert_management_alert' do
+          get '', on: :member, action: :details, as: ''
+        end
+
         get 'work_items/*work_items_path' => 'work_items#index', as: :work_items
 
         resource :tracing, only: [:show]

lib/api/entities/alert_management/alert.rb

+# frozen_string_literal: true
+
+module API
+  module Entities
+    module AlertManagement
+      class Alert < Grape::Entity
+        expose :iid
+        expose :title
+      end
+    end
+  end
+end

lib/api/entities/todo.rb

@@ -33,7 +33,7 @@ module API
       def todo_target_url(todo)
         return design_todo_target_url(todo) if todo.for_design?
 
-        target_type = todo.target_type.underscore
+        target_type = todo.target_type.constantize.model_name.param_key
         target_url = "#{todo.resource_parent.class.to_s.underscore}_#{target_type}_url"
 
         Gitlab::Routing