Introduce copy constructor and assignment operator for vk::raii classes that hold handles without a destructor.

tests/ArrayProxy/ArrayProxy.cpp

@@ -31,7 +31,7 @@ int main( int /*argc*/, char ** /*argv*/ )
   try
   {
     // to prevent a warning on unreferenced function vk::getDispatchLoaderStatic, use just one arbitrary vk-function
-    vk::enumerateInstanceVersion();
+    (void)vk::enumerateInstanceVersion();
 
     // nullptr_t
     fct( nullptr );