Send wxEVT_DATAVIEW_ITEM_EDITING_DONE after cancelling too

Previously this event was not sent at all if editing the item was
cancelled, e.g. by pressing Esc.

Do send it now from the generic implementation and update the sample to
show this event.

See #17835.

docs/changes.txt

@@ -182,6 +182,7 @@ All (GUI):
 - Generate wxEVT_SEARCH on Enter under all platforms.
 - Extend wxRendererNative::DrawGauge() to work for vertical gauges too.
 - Add wxHD_BITMAP_ON_RIGHT style to wxHeaderCtrl.
+- Send wxEVT_DATAVIEW_ITEM_EDITING_DONE when editing was cancelled too.
 
 wxGTK: