Move d3d11 device, memory, buffer pool and minimal method
to gst-libs so that other plugins can access d3d11 resource.
Since Direct3D is primary graphics API on Windows, we need
this infrastructure for various plugins can share GPU resource
without downloading GPU memory.
Note that this implementation is public only for -bad scope
for now.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/464>
In some cases, rendering and dxgi (e.g., swapchain) APIs should be
called from window message pump thread, but current design (dedicated d3d11 thread)
make it impossible. To solve it, change concurrency model to locking based one
from single-thread model.
