hotspots: Add backend support for tutorial hotspots.

This commit adds the backend support for a new style of tutorial which
allows for highlighting of multiple areas of the page with hotspots that
disappear when clicked by the user.

zerver/views/home.py

@@ -283,6 +283,7 @@ def home_real(request):
         'attachments',
         'default_language',
         'emoji_alt_code',
+        'hotspots',
         'last_event_id',
         'left_side_userlist',
         'max_icon_file_size',