Preserve size of wxGrid rows/columns when hiding and showing them back.

Preserve size of wxGrid rows/columns when hiding and showing them back.

Previously, if a wxGrid row or column was hidden by setting its size to 0, its
original size was lost. Change this so that it's preserved now and can be
restored by setting the size to the special -1 value later.

Closes #14133.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72491 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775