DEV: Add outlet wrapper to categories only component (#28669)

app/assets/javascripts/discourse/app/components/categories-only.hbs

@@ -1,3 +1,7 @@
+<PluginOutlet
+  @name="categories-only-wrapper"
+  @outletArgs={{hash categories=this.categories}}
+>
   {{#if this.categories}}
     {{#if this.filteredCategories}}
       <table class="category-list {{if this.showTopics 'with-topics'}}">
@@ -27,7 +31,11 @@
 
     {{#if this.mutedCategories}}
       <div class="muted-categories">
-      <a href class="muted-categories-link" {{on "click" this.toggleShowMuted}}>
+        <a
+          href
+          class="muted-categories-link"
+          {{on "click" this.toggleShowMuted}}
+        >
           <h3 class="muted-categories-heading">{{i18n "categories.muted"}}</h3>
           {{#if this.mutedToggleIcon}}
             {{d-icon this.mutedToggleIcon}}
@@ -64,6 +72,7 @@
       </div>
     {{/if}}
   {{/if}}
+</PluginOutlet>
 
 <PluginOutlet
   @name="below-categories-only"