Add shaders re-implemented in HLSL

These were written against the shaders at revision eddd724e7.
There have been changes made since then, which will need to be mirrored.

See `data/hlsl/README.md` for the current status of each sample.

data/hlsl/stencilbuffer/outline.vert

@@ -0,0 +1,24 @@
+// Copyright 2020 Google LLC
+
+struct VSInput
+{
+[[vk::location(0)]] float4 Pos : POSITION0;
+[[vk::location(2)]] float3 Normal : NORMAL0;
+};
+
+struct UBO
+{
+	float4x4 projection;
+	float4x4 model;
+	float4 lightPos;
+	float outlineWidth;
+};
+
+cbuffer ubo : register(b0) { UBO ubo; }
+
+float4 main(VSInput input) : SV_POSITION
+{
+	// Extrude along normal
+	float4 pos = float4(input.Pos.xyz + input.Normal * ubo.outlineWidth, input.Pos.w);
+	return mul(ubo.projection, mul(ubo.model, pos));
+}