added comment section on card details to avoid loading the card comment activities from the server

- and added to show only the activities a card

- to display the card comments a connection to the server was needed to get the activities of the card comments, now, it's not necessary
- also performance relevant. until now there were a lot of activities loaded, now only of the current card

client/components/sidebar/sidebar.jade

@@ -28,9 +28,16 @@ template(name='homeSidebar')
       .materialCheckBox(class="{{#if hiddenMinicardLabelText}}is-checked{{/if}}")
   hr
   unless currentUser.isNoComments
-    h3
+    h3.activity-title
       i.fa.fa-comments-o
       | {{_ 'activities'}}
+
+      .material-toggle-switch(title="{{_ 'show-activities'}}")
+        if showActivities
+          input.toggle-switch(type="checkbox" id="toggleShowActivitiesBoard" checked="checked")
+        else
+          input.toggle-switch(type="checkbox" id="toggleShowActivitiesBoard")
+        label.toggle-label(for="toggleShowActivitiesBoard")
     +activities(mode="board")
 
 template(name="membersWidget")

client/components/sidebar/sidebar.js

@@ -136,7 +136,7 @@ BlazeComponent.extendComponent({
 
 Blaze.registerHelper('Sidebar', () => Sidebar);
 
-Template.homeSidebar.helpers({
+BlazeComponent.extendComponent({
   hiddenMinicardLabelText() {
     currentUser = ReactiveCache.getCurrentUser();
     if (currentUser) {
@@ -147,7 +147,20 @@ Template.homeSidebar.helpers({
       return false;
     }
   },
-});
+  showActivities() {
+    let ret = Utils.getCurrentBoard().showActivities ?? false;
+    return ret;
+  },
+  events() {
+    return [
+      {
+        'click #toggleShowActivitiesBoard'() {
+          Utils.getCurrentBoard().toggleShowActivities();
+        },
+      },
+    ];
+  },
+}).register('homeSidebar');
 
 Template.boardInfoOnMyBoardsPopup.helpers({
   hideCardCounterList() {