Handle multiple levels of namespace nesting when generating routes

[jagthedrummer]

When doing this:

bin/rails generate super_scaffold Task Team name:text_field
bin/rails generate super_scaffold Project Team name:text_field
bin/rails generate super_scaffold Projects::Milestone Project,Team name:text_field
bin/rails generate super_scaffold Projects::Milestones::IncludedTask Projects::Milestone,Project,Team task_id:super_select{class_name=Task} details:text_field --sortable

We used to incorrectly nest the routes like this:

resources :tasks

resources :projects do
  scope module: 'projects' do
    resources :milestones, only: collection_actions do
      # ⚠️ This is in the wrong place!
      scope module: 'milestones' do
        resources :included_tasks, only: collection_actions, concerns: [:sortable]
      end
    end

    namespace :milestones do
      resources :included_tasks, except: collection_actions, concerns: [:sortable]
    end
  end
end

namespace :projects do
  resources :milestones, except: collection_actions
end

This PR makes it so that we nest the routes correctly like this:

resources :tasks

resources :projects do
  scope module: 'projects' do
    resources :milestones, only: collection_actions

    namespace :milestones do
      resources :included_tasks, except: collection_actions, concerns: [:sortable]
    end
  end
end

namespace :projects do
  resources :milestones, except: collection_actions do 
    # ✅ This is the right place to put this!
    scope module: 'milestones' do
      resources :included_tasks, only: collection_actions, concerns: [:sortable]
    end
  end
end

Fixes: bullet-train-co/bullet_train#1655