VS: Run VSWindowsFormsResx test only with normal toolset

If CMAKE_TEST_GENERATOR_TOOLSET is set then the test toolset may
not support Windows Forms even though the default toolset does.
VS: Add Windows Forms Support

Add support to maintain designer functionality for Visual Studio C++
Windows Forms projects.  Also add a test project showing how to use
the CMakeLists.txt file and, when successfully configured, will allow
use of the designer for the included form.
Merge topic 'vs-windows-forms' into next

2a67dbc VS: Run VSWindowsFormsResx test only with normal toolset
Merge topic 'vs-windows-forms' into next

79ec786 VS: Add Windows Forms Support