Add non-prefixed polymorphic admin routes

These routes are solved in a different way because of an inconsistency:
we define `groups` and `budget_investments`; we should either use the
`budget_` prefix in all places or remove it everywhere.

We can now share code using `polymorphic_path` even with these models.

config/initializers/routes_hierarchy.rb

@@ -2,9 +2,9 @@
 # routes with nested resources in the admin namespace
 module ActionDispatch::Routing::UrlFor
   def resource_hierarchy_for(resource)
-    if polymorphic_mapping(resource)
-      resolve = polymorphic_mapping(resource).send(:eval_block, self, resource, {})
+    resolve = resolve_for(resource)
 
+    if resolve
       if resolve.last.is_a?(Hash)
         [resolve.first, *resolve.last.values]
       else
@@ -16,6 +16,20 @@ module ActionDispatch::Routing::UrlFor
   end
 
   def admin_polymorphic_path(resource, options = {})
-    polymorphic_path([:admin, *resource_hierarchy_for(resource)], options)
+    if %w[Budget::Group Budget::Heading Poll::Booth Poll::Officer
+          Poll::Question Poll::Question::Answer::Video].include?(resource.class.name)
+      resolve = resolve_for(resource)
+      resolve_options = resolve.pop
+
+      polymorphic_path([:admin, *resolve], options.merge(resolve_options))
+    else
+      polymorphic_path([:admin, *resource_hierarchy_for(resource)], options)
+    end
   end
+
+  private
+
+    def resolve_for(resource)
+      polymorphic_mapping(resource)&.send(:eval_block, self, resource, {})
+    end
 end