Recognize old wx{CHB,LB}_XXX styles in XRC.

Recognize old wx{CHB,LB}_XXX styles in XRC.

Situation with wxBK_XXX vs wxXXB_XXX remains confusing, the comments in the
code suggest that the former is preferred but the latter are documented for
wxListbook and wxChoicebook (although they don't even exist for wxTreebook).
So it seems unwise to not recognize the wxXXB_XXX versions in XRC as people
could easily decide to use them instead of wxBK_XXX values -- and this is also
consisten with wxNotebookXmlHandler which does recognize both wxBK_XXX and
wxNB_XXX already.

Change wxListbookXmlHandler and wxChoicebookXmlHandler to also always
recognize these styles.

Closes #10725.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61999 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775