Make wxToolBar styles consistent and add wxTB_DEFAULT_STYLE.

Don't include wxBORDER_NONE in neither wxToolBar ctor and Create() nor
wxFrame::CreateToolBar() flags parameter, override GetDefaultBorder() in
wxToolBar itself instead to use the border style appropriate for the current
platform by default. This has the same effect -- the default border style is
used unless another one is explicitly specified -- but is more clear and
consistent.

Also add wxTB_DEFAULT_STYLE for consistency with the other classes.

Closes #15037.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73757 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/frame.h

@@ -274,7 +274,7 @@ public:
 
         @see CreateStatusBar(), OnCreateToolBar(), SetToolBar(), GetToolBar()
     */
-    virtual wxToolBar* CreateToolBar(long style = wxBORDER_NONE | wxTB_HORIZONTAL,
+    virtual wxToolBar* CreateToolBar(long style = wxTB_DEFAULT_STYLE,
                                      wxWindowID id = wxID_ANY,
                                      const wxString& name = wxToolBarNameStr);