DEV: Introduce faker.js for use in tests & styleguide (#26533)

Available as a normal synchronous module in tests
Available as an async import in core, or via the `loadFaker` helper in themes/plugins (which cannot use async import directly)

plugins/styleguide/assets/javascripts/discourse/components/sections/organisms/modal.js

@@ -1,15 +1,18 @@
 import Component from "@glimmer/component";
 import { tracked } from "@glimmer/tracking";
 import { action } from "@ember/object";
+import { service } from "@ember/service";
 import I18n from "discourse-i18n";
 
 export default class extends Component {
+  @service styleguide;
+
   @tracked inline = true;
   @tracked hideHeader = false;
   @tracked dismissable = true;
   @tracked modalTagName = "div";
   @tracked title = I18n.t("styleguide.sections.modal.header");
-  @tracked body = this.args.dummy.shortLorem;
+  @tracked body = this.styleguide.faker.lorem.lines(5);
   @tracked subtitle = "";
   @tracked flash = "";
   @tracked flashType = "success";

plugins/styleguide/assets/javascripts/discourse/routes/styleguide.js

@@ -1,8 +1,12 @@
 import Route from "@ember/routing/route";
+import { service } from "@ember/service";
 import { allCategories } from "discourse/plugins/styleguide/discourse/lib/styleguide";
 
 export default class Styleguide extends Route {
-  model() {
+  @service styleguide;
+
+  async model() {
+    await this.styleguide.ensureFakerLoaded(); // So that it can be used synchronously in styleguide components
     return allCategories();
   }
 

plugins/styleguide/assets/javascripts/discourse/services/styleguide.js

@@ -0,0 +1,10 @@
+import Service from "@ember/service";
+import loadFaker from "discourse/lib/load-faker";
+
+export default class StyleguideService extends Service {
+  faker;
+
+  async ensureFakerLoaded() {
+    this.faker ||= (await loadFaker()).faker;
+  }
+}