d3d11videosink: Add support for overlay composition

d3d11videosink: Add support for overlay composition

Add d3d11overlaycompositor object to draw overlay image
on render target using Blend method.

d3d11: Try to pop d3d11 sdk layer debug message on failure

And activate d3d11 sdk layer for debug build, since it might introduce
overhead.

Closes: #1149 (closed)