Improve support for TABs in wxListBox under MSW

Always set the LB_USETABSTOPS style flag to achieve behaviour more
compatible with other platforms and expand TABs to align them at tab
stops positioned at every 8 characters.

Also add MSW-specific MSWSetTabStops() method allowing to customize tab
stops.

Update the documentation and the sample to demonstrate using TABs.

Closes https://github.com/wxWidgets/wxWidgets/pull/1789

src/msw/listbox.cpp

@@ -187,6 +187,9 @@ WXDWORD wxListBox::MSWGetStyle(long style, WXDWORD *exstyle) const
     }
 #endif // wxUSE_OWNER_DRAWN
 
+    // tabs stops are expanded by default on linux/GTK and macOS/Cocoa
+    msStyle |= LBS_USETABSTOPS;
+
     return msStyle;
 }
 
@@ -611,6 +614,12 @@ void wxListBox::SetHorizontalExtent(const wxString& s)
     //else: it shouldn't change
 }
 
+bool wxListBox::MSWSetTabStops(const wxVector<int>& tabStops)
+{
+    return SendMessage(GetHwnd(), LB_SETTABSTOPS, (WPARAM)tabStops.size(),
+                       tabStops.size() ? (LPARAM)tabStops.begin() : NULL);
+}
+
 wxSize wxListBox::DoGetBestClientSize() const
 {
     // find the widest string