layers: GH535 Add checks for Clear image errors
layers: GH535 Add checks for Clear image errors

This adds two new checks to make sure that CmdClearColorImage is
not called with depth/stencil format image and that
CmdClearDepthStencilImage is not called with color format image.

Also add getImageState() helper function to image layer to
simplify/unify code for lookup of IMAGE_STATE from imageMap.

Radamanthe/VulkanSamples,Radamanthe/VulkanSamples,Radamanthe/VulkanSamples,Radamanthe/VulkanSamples,Radamanthe/VulkanSamples,Radamanthe/VulkanSamples