tests: Add positive test ValidRenderPassAttachmentLayoutWithLoadOp
tests: Add positive test ValidRenderPassAttachmentLayoutWithLoadOp

Positive test case where a renderpass attachment that has LOAD_OP_CLEAR
is used in a subsequent subpass as READ_ONLY. Previously we had a bug
where any subsequent uses (beyond first use) in READ_ONLY layout would
incorrectly trigger an error.

elongbug/Vulkan-LoaderAndValidationLayers,elongbug/Vulkan-LoaderAndValidationLayers,elongbug/Vulkan-LoaderAndValidationLayers,elongbug/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers