FEATURE: Allow theme tests to be run in production (#12815)

This commit allows site admins to run theme tests in production via a new `/theme-qunit` route. When you visit `/theme-qunit`, you'll see a list of the themes/components installed on your site that have tests, and from there you can select a theme or component that you run its tests.

We also have a new rake task `themes:install_and_test` that can be used to install a list of themes/components on a temporary database and run the tests of the themes/components that are installed. This rake task can be useful when upgrading/deploying a Discourse instance to make sure that the installed themes/components are compatible with the new Discourse version being deployed, and if the tests fail you can abort the build/deploy process so you don't end up with a broken site.

app/helpers/qunit_helper.rb

@@ -2,23 +2,14 @@
 
 module QunitHelper
   def theme_tests
-    theme_ids = request.env[:resolved_theme_ids]
-    return "" if theme_ids.blank?
+    theme = Theme.find_by(id: request.env[:resolved_theme_ids]&.first)
+    return "" if theme.blank?
 
-    skip_transformation = request.env[:skip_theme_ids_transformation]
-    query = ThemeField
-      .joins(:theme)
-      .where(
-        target_id: Theme.targets[:tests_js],
-        theme_id: skip_transformation ? theme_ids : Theme.transform_ids(theme_ids)
-      )
-      .pluck(:theme_id)
-      .uniq
-      .map do |theme_id|
-        src = "#{GlobalSetting.cdn_url}#{Discourse.base_path}/theme-javascripts/tests/#{theme_id}.js"
-        "<script src='#{src}'></script>"
-      end
-      .join("\n")
-      .html_safe
+    _, digest = theme.baked_js_tests_with_digest
+    src = "#{GlobalSetting.cdn_url}" \
+      "#{Discourse.base_path}" \
+      "/theme-javascripts/tests/#{theme.id}-#{digest}.js" \
+      "?__ws=#{Discourse.current_hostname}"
+    "<script src='#{src}'></script>".html_safe
   end
 end