Configure CORS settings for StoriesController

- Storybook need to access through a GET method on `/rails/stories/**` served by `ViewComponent::Storybook::StoriesController`
 - Configure exact policy with an initialized filter

config/initializers/storybook.rb

@@ -0,0 +1,14 @@
+# Adjust headers to allow running Storybook in development.
+# Uses iframes and doesn't play nicely with CORS checks
+
+if Rails.env.development?
+  module PermissiveCORSHeaders
+    def self.before(response)
+      response.headers["Access-Control-Allow-Origin"] = "*"
+      response.headers["Access-Control-Allow-Methods"] = "GET"
+    end
+  end
+
+  ViewComponent::Storybook::StoriesController.before_action(PermissiveCORSHeaders)
+end
+