Fix wxURL copy ctor and assignment: the default ones provided by the compiler are wrong because wxURL uses pointers internally.
Also add a test for copy & assignment in URLTestCase.
Closes#11223
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63806 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775