Don't keep out of date column widths in generic wxDataViewCtrl.

The cached widths need to be invalidated whenever an item is expanded or
collapsed, whether it's done programmatically (which was already handled) or
interactively by the user (which wasn't).

Closes #16678.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@78218 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775