DEV: adds a few plugin outlets required for themes (#9929)

app/assets/javascripts/discourse/app/templates/components/composer-toggles.hbs

@@ -1,4 +1,6 @@
 <div class="composer-controls">
+  {{plugin-outlet name="before-composer-toggles"}}
+
   {{#if site.mobileView}}
     {{flat-button
       class="toggle-toolbar"

app/assets/javascripts/discourse/app/templates/discovery.hbs

@@ -14,6 +14,8 @@
 
   {{conditional-loading-spinner condition=loading}}
 
+  {{plugin-outlet name="discovery-above"}}
+
   <div class="container list-container {{if loading "hidden"}}">
     <div class="row">
       <div class="full-width">

app/assets/javascripts/discourse/app/templates/discovery/topics.hbs

@@ -42,6 +42,8 @@
       {{period-chooser period=period action=(action "changePeriod") fullDay=false}}
     </div>
   {{else}}
+    {{plugin-outlet name="before-topic-list" args=(hash category=category)}}
+
     {{#if topicTrackingState.hasIncoming}}
       <div class="show-more {{if hasTopics "has-topics"}}">
         <a tabindex="0" href {{action "showInserted"}} class="alert alert-info clickable">
@@ -73,6 +75,8 @@
       scrollOnLoad=true
       onScroll=discoveryTopicList.saveScrollPosition}}
   {{/if}}
+
+  {{plugin-outlet name="after-topic-list" args=(hash category=category)}}
 {{/discovery-topics-list}}
 
 <footer class="topic-list-bottom">