Fix status reporting of speech modes checkboxes (#16006)
Fixes #16005.
Summary of the issue:
When enabling/disabling checkboxes in the speech modes list, under voice settings, the new status was not reported by speech or Braille.
Description of user facing changes
Now user hears "enabled" or "disabled", and gets his Braille display refreshed.
Description of development approach
PR #15960 has introduced a new handler of EVT_CHECKLISTBOX event for speechModesList.
But this latter is an nvdaControls.CustomCheckListBox, that already defines an handler for that event, to fix specifically this accessibility issue of wx.
So I simply put evt.Skip() at the beginning of new handler, to propagate event to custom control handler.
