Avoid storybook deprecation warning

Loading the engine directly is deprecated and I followed the current
documentation to load storybook in the app. This avoids a warning:

> DEPRECATION WARNING: This manually engine loading is deprecated and will be removed in v1.0.0. Remove `require "view_component/storybook/engine"`. (called from <top (required)> at config/application.rb:30)

Gemfile

@@ -178,7 +178,7 @@ group :development do
   gem 'spring-commands-rspec'
   gem 'web-console'
 
-  gem "view_component_storybook", require: "view_component/storybook/engine"
+  gem "view_component_storybook"
 
   gem 'rack-mini-profiler', '< 3.0.0'
 end

config/application.rb

@@ -20,6 +20,9 @@ require "rails"
   end
 end
 
+require "view_component"
+require "view_component/storybook"
+
 require_relative "../lib/open_food_network/i18n_config"
 require_relative '../lib/spree/core/environment'
 require_relative '../lib/spree/core/mail_interceptor'