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/deferredshadows/mrt.vert

@@ -0,0 +1,52 @@
+// Copyright 2020 Google LLC
+
+struct VSInput
+{
+[[vk::location(0)]] float4 Pos : POSITION0;
+[[vk::location(1)]] float2 UV : TEXCOORD0;
+[[vk::location(2)]] float3 Color : COLOR0;
+[[vk::location(3)]] float3 Normal : NORMAL0;
+[[vk::location(4)]] float3 Tangent : TEXCOORD1;
+};
+
+struct UBO
+{
+	float4x4 projection;
+	float4x4 model;
+	float4x4 view;
+	float4 instancePos[3];
+};
+
+cbuffer ubo : register(b0) { UBO ubo; }
+
+struct VSOutput
+{
+	float4 Pos : SV_POSITION;
+[[vk::location(0)]] float3 Normal : NORMAL0;
+[[vk::location(1)]] float2 UV : TEXCOORD0;
+[[vk::location(2)]] float3 Color : COLOR0;
+[[vk::location(3)]] float3 WorldPos : POSITION0;
+[[vk::location(4)]] float3 Tangent : TEXCOORD1;
+};
+
+VSOutput main(VSInput input, uint InstanceIndex : SV_InstanceID)
+{
+	VSOutput output = (VSOutput)0;
+	float4 tmpPos = input.Pos + ubo.instancePos[InstanceIndex];
+
+	output.Pos = mul(ubo.projection, mul(ubo.view, mul(ubo.model, tmpPos)));
+
+	output.UV = input.UV;
+	output.UV.y = 1.0 - output.UV.y;
+
+	// Vertex position in world space
+	output.WorldPos = mul(ubo.model, tmpPos).xyz;
+
+	// Normal in world space
+	output.Normal = normalize(input.Normal);
+	output.Tangent = normalize(input.Tangent);
+
+	// Currently just vertex color
+	output.Color = input.Color;
+	return output;
+}