FIX: try using new component style

Author: angusmcleod

assets/javascripts/discourse/templates/admin-wizards-manager.hbs

@@ -11,11 +11,11 @@
       </div>
     {{/if}}
 
-    {{input
+    <Input
       id="file-upload"
-      type="file"
+      @type="file"
       accept="application/json"
-      input=(action "setFile")}}
+      {{on "input" (action "setFile" value="target.value")}} />
     {{d-button
       id="upload-button"
       label="admin.wizard.manager.upload"