Implement DoGetSizeFromTextSize() for wxMSW wx{Choice,Combobox,TextCtrl}.

Refactor and improve the existing DoGetBestSize() implementations to use
DoGetBestSize().

Closes #14816.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72954 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/combobox.h

@@ -132,6 +132,8 @@ protected:
     virtual void DoSetToolTip(wxToolTip *tip);
 #endif
 
+    virtual wxSize DoGetSizeFromTextSize(int xlen, int ylen = -1) const;
+
     // this is the implementation of GetEditHWND() which can also be used when
     // we don't have the edit control, it simply returns NULL then
     //