gdi32: Store the full flags in the face object, and add a flag for fonts added through AddFontResource.

Having both a "hwnd" and a "window" here doesn't exactly make things much
easier to follow.

We want this to happen after ddraw_destroy_swapchain() in particular, because
dest_window being different from d3d_window will cause it to destroy
d3d_window, but this seems like a good idea in general.

In particular, test that the windows aren't destroyed by accident.