Add link to watch history in feed and manager

src/invidious/views/subscription_manager.ecr

@@ -3,9 +3,14 @@
 <% end %>
 
 <div class="pure-g h-box">
-    <div class="pure-u-2-3">
+    <div class="pure-u-1-3">
         <h3><span id="count"><%= subscriptions.size %></span> subscriptions</h3>
     </div>
+    <div class="pure-u-1-3" style="text-align:center;">
+        <h3>
+            <a href="/feed/history">Watch history</a>
+        </h3>
+    </div>
     <div class="pure-u-1-3" style="text-align:right;">
         <h3>
             <a href="/data_control?referer=<%= referer %>">Import/Export</a>

src/invidious/views/subscriptions.ecr

@@ -3,11 +3,16 @@
 <% end %>
 
 <div class="pure-g h-box">
-    <div class="pure-u-2-3">
+    <div class="pure-u-1-3">
         <h3>
             <a href="/subscription_manager">Manage subscriptions</a>
         </h3>
     </div>
+    <div class="pure-u-1-3" style="text-align:center;">
+        <h3>
+            <a href="/feed/history">Watch history</a>
+        </h3>
+    </div>
     <div class="pure-u-1-3" style="text-align:right;">
         <h3>
             <a href="/feed/private?token=<%= user.token %>"><i class="icon ion-logo-rss"></i></a>