Auto grow the last wxDataViewCtrl column on all platforms.

The GTK+ implementation always did this and it doesn't make much sense
to let the space be wasted, so do as GTK+ does: expand the last column
to cover the remaining unused space in the OS X and generic
implementations too.  Don't do anything if the space is insufficient.
Respect the last column's minimal width.

See #13904.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75347 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775