DEV: Remove 'htmlSafe' string prototype extensions (#16766)

Context: https://deprecations.emberjs.com/v3.x/#toc_ember-string-prototype_extensions

app/assets/javascripts/select-kit/addon/components/multi-select/selected-category.js

@@ -2,15 +2,18 @@ import SelectedNameComponent from "select-kit/components/selected-name";
 import { categoryBadgeHTML } from "discourse/helpers/category-link";
 import { computed } from "@ember/object";
 import layout from "select-kit/templates/components/multi-select/selected-category";
+import { htmlSafe } from "@ember/template";
 
 export default SelectedNameComponent.extend({
   classNames: ["selected-category"],
   layout,
 
   badge: computed("item", function () {
-    return categoryBadgeHTML(this.item, {
-      allowUncategorized: true,
-      link: false,
-    }).htmlSafe();
+    return htmlSafe(
+      categoryBadgeHTML(this.item, {
+        allowUncategorized: true,
+        link: false,
+      })
+    );
   }),
 });

app/assets/javascripts/select-kit/addon/components/multi-select/selected-color.js

@@ -1,11 +1,14 @@
 import SelectedNameComponent from "select-kit/components/selected-name";
 import discourseComputed from "discourse-common/utils/decorators";
+import { htmlSafe } from "@ember/template";
 
 export default SelectedNameComponent.extend({
   classNames: ["select-kit-selected-color"],
 
   @discourseComputed("name")
   footerContent(name) {
-    return `<span class="color-preview" style="background:#${name}"></span>`.htmlSafe();
+    return htmlSafe(
+      `<span class="color-preview" style="background:#${name}"></span>`
+    );
   },
 });