Remove WinDriver.cpp from test suites

WinDriver.cpp was required for the old MFC-based test runner, which is no longer included. So this file can be safely removed from all projects. Also, in the test suite's CMakeLists.txt, the following must be removed:

# WinDriver depends on WinTestRunner which depends on MFC, and we don't want that
POCO_SOURCES_AUTO_PLAT(TEST_SRCS OFF
	src/WinDriver.cpp
)