Because DXGI flip mode swapchain will disallow GDI operation
to a HWND once swapchain is configured, videosink has been creating
child window of application's window. However, since window creation
would take a few milliseconds, it can cause performance issue such as
UI freezing. Adding a property so that videosink can attach
DXGI swapchain diretly to application's window in order to improve
performance.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7013>
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