Add wxVersionInfo and functions returning it for 3rd party libraries.

Add simple wxVersionInfo class holding the version information.

Also add GetLibraryVersionInfo() static method to wx{JPEG,PNG,TIFF}Handler,
wxStyledTextCtrl and wxXmlDocument classes and wxGetZlibVersionInfo() and
wxGetLibraryVersionInfo() global functions using it.

Closes #12690.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66259 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/stc/stc.cpp

@@ -4618,4 +4618,9 @@ wxStyledTextEvent::wxStyledTextEvent(const wxStyledTextEvent& event):
 //----------------------------------------------------------------------
 //----------------------------------------------------------------------
 
+/*static*/ wxVersionInfo wxStyledTextCtrl::GetLibraryVersionInfo()
+{
+    return wxVersionInfo("Scintilla", 2, 3);
+}
+
 #endif // wxUSE_STC