added shortcut for closing the editor dialog

Author: skttl

src/Our.Umbraco.DocTypeGridEditor/Web/UI/App_Plugins/DocTypeGridEditor/Views/doctypegrideditor.dialog.html

@@ -35,6 +35,7 @@
                 <umb-button type="button"
                             button-style="link"
                             label-key="general_close"
+                            shortcut="esc"
                             action="vm.close()">
                 </umb-button>
                 <umb-button type="button"