render graph cannot present depth image

It is impossible to transfer depth image to RGBA image by using blitImage (see [present callback](https://github.com/vkdev-team/VulkanAbstractionLayer/blob/master/VulkanAbstractionLayer/RenderGraphBuilder.cpp#L625)). But depth image output is useful for debugging, so we need to somehow copy it to present image

Start in RenderGraphBuilder.cpp at the present callback around line 625 and inspect how blitImage handles the depth image and RGBA present image. Determine a supported copy path for depth output used for debugging; done means the render graph can present that depth result in the present image without the current blitImage limitation.

Written by the indexing model from the issue text.