MDL-64099 message: Make collapsible headers bold

theme/bootstrapbase/less/moodle/message.less

@@ -1268,6 +1268,12 @@
         text-decoration: none;
         color: inherit;
     }
+    .btn-link {
+        &:hover,
+        &:focus {
+            text-decoration: none;
+        }
+    }
 
     .message {
         p {

theme/bootstrapbase/style/moodle.css

@@ -9180,6 +9180,10 @@ a.ygtvspacer:hover {
   text-decoration: none;
   color: inherit;
 }
+.message-drawer .btn-link:hover,
+.message-drawer .btn-link:focus {
+  text-decoration: none;
+}
 .message-drawer .message p {
   margin: 0;
 }

theme/bootstrapbase/templates/core_message/message_drawer_view_overview_section.mustache

@@ -35,6 +35,7 @@
     adding ".in" to ".show"
     adding .accordion-group to the main container div
     adding expanded to the .accordion-group if required for toggle icons to work.
+    changing span.font-weight-bold to strong
 
     Example context (json):
     {}
@@ -59,7 +60,7 @@
             <span class="expanded-icon-container">
                 {{#pix}} t/expanded, core {{/pix}}
             </span>
-            {{$title}}{{/title}}
+            <strong>{{$title}}{{/title}}</strong>
             <span class="hidden ml-1" data-region="section-total-count-container">
                 (<span data-region="section-total-count">{{count.total}}</span>)
             </span>
@@ -79,4 +80,4 @@
             data-parent="#message-drawer-view-overview-container"
         {{/rootattributes}}
     {{/ core_message/message_drawer_lazy_load_list }}
-</div>
+</div>