Fix various team accessibility issues.

Authors:
  - Peter Fogg
  - Daniel Friedman

TNL-1953

lms/templates/components/card/card.underscore

@@ -4,7 +4,12 @@
         <% if (pennant) { %>
             <small class="card-type"><%- pennant %></small>
         <% } %>
-        <h3 class="card-title"><%- title %></h3>
+        <h3 class="card-title"
+            <% if (!_.isUndefined(srInfo)) { %>
+                aria-describedby="<%= srInfo.id %>"
+            <% } %>
+            ><%- title %>
+        </h3>
         <p class="card-description"><%- description %></p>
     </div>
 </div>
@@ -21,7 +26,12 @@
         <% if (pennant) { %>
             <small class="card-type"><%- pennant %></small>
         <% } %>
-        <h3 class="card-title"><%- title %></h3>
+        <h3 class="card-title"
+            <% if (!_.isUndefined(srInfo)) { %>
+                aria-describedby="<%= srInfo.id %>"
+            <% } %>
+            ><%- title %>
+        </h3>
         <p class="card-description"><%- description %></p>
     </div>
     <div class="card-actions">

lms/templates/components/header/header.underscore

@@ -1,7 +1,7 @@
 <header class="page-header has-secondary">
     <div class="page-header-main">
         <% if (breadcrumbs !== null && breadcrumbs.length > 0) { %>
-            <nav class="breadcrumbs">
+            <nav class="breadcrumbs" aria-label="<%- nav_aria_label %>">
             <% _.each(breadcrumbs, function (breadcrumb) { %>
                 <a class="nav-item" href="<%= breadcrumb.url %>"><%- breadcrumb.title %></a>
                 <span class="icon fa-angle-right" aria-hidden="true"></span>

lms/templates/components/tabbed/tab.underscore

@@ -1 +1 @@
-<a class="nav-item" href="" data-url="<%= url %>" data-index="<%= index %>" role="tab" aria-selected="false"><%- title %></a>
+<a class="nav-item" href="" data-url="<%= url %>" data-index="<%= index %>" role="tab" aria-selected="false"><%= title %></a>