* Graphics: Integrate RenderTarget in FrameGraph
- This handles the blit to texture/swapchain in the FrameGraph and fixes RenderTextureBlit
- Dummy attachments were added to the FrameGraph class to handle link without texture (used to setup a dependency between two passes with no texture)
- FramePass now supports custom access/layout/usage for inputs
* Graphics/RenderTarget: Allow to set any RenderTarget as output
This changes makes the whole rendering independent from the RenderFrame acquired from the Swapchain.
This may allow to do offscreen rendering (= without swapchain), or multi-window rendering in the future
Jérôme Leclercq