Multisamples issues in Vulkan

[jesusdesantos]

In Vulkan when creating pipelines, the sample count must be indicated in VkPipelineMultisampleStateCreateInfo. The pipeline can't be later used with a rendertarget with a different sample count.

A native plugin doesn't receive information about the sample count of the current active render pass. I think this could be added to UnityVulkanRecordingState.

Note that the Vulkan example provided in this repository has hardcoded the sample count and doesn't work with cameras using MSAA.