msxml3/tests: Add some tests for IVBSAXContentHandler::startElement() and IVBSAXContentHandler::endElement().

These are mostly a copy of ISAXContentHandler::startElement() and
ISAXContentHandler::endElement() tests.
Signed-off-by: Dmitry Timoshkov <dmitry@baikal.ru>
Signed-off-by: Nikolay Sivov <nsivov@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>