SwiftShader doesn't copy vk_swiftshader_icd.json to output directory

[xen2]

Summary

Silk.NET.Vulkan.SwiftShader.Native copies only the native library but doesn't copy the vk_swiftshader_icd.json file (which is necessary to use SwiftShader with VK_DRIVER_FILES).

Optional (not sure if necessary): SwiftShader still generate json file with "api_version": "1.0.5" but I think it should be 1.3.0.

Steps to reproduce

• Platform: Desktop
• Framework Version: .NET Core 3, .NET 4.8, Xamarin Android 8.1
• API: Vulkan

1. Reference Silk.NET.Vulkan.SwiftShader.Native
2. Build project
3. Check output dir