Expose hidden status of component examples in packaged fixtures

In order for downstream projects to use the component examples for
rendering as well as for tests, it is useful to know which examples
should be hidden from display since they were designed for tests only.

tasks/gulp/copy-to-destination.js

@@ -70,7 +70,8 @@ function generateFixtures (file) {
         const fixture = {
           name: example.name,
           options: example.data,
-          html: nunjucks.render(componentTemplatePath, { params: example.data }).trim()
+          html: nunjucks.render(componentTemplatePath, { params: example.data }).trim(),
+          hidden: example.hidden
         }
 
         fixtures.fixtures.push(fixture)