Add icon for new directory source plugin

Author: ohinckel

common/jinja2/common/base.library.html

@@ -79,6 +79,7 @@
 
   'source.plugin.network': 'cloud-arrow-down',
   'source.plugin.data': 'shuffle',
+  'source.plugin.dir': 'folder',
   'source.instance' : 'object-group',
   'source.input' : 'file-import',
   'source.output' : 'file-export',