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/computecloth/sphere.vert

@@ -0,0 +1,41 @@
+// Copyright 2020 Google LLC
+
+struct VSInput
+{
+[[vk::location(0)]]float3 Pos : POSITION0;
+[[vk::location(2)]]float3 Normal : NORMAL0;
+};
+
+struct VSOutput
+{
+	float4 Pos : SV_POSITION;
+[[vk::location(0)]] float3 Normal : NORMAL0;
+[[vk::location(1)]] float3 ViewVec : TEXCOORD0;
+[[vk::location(2)]] float3 LightVec : TEXCOORD1;
+};
+
+
+struct UBO
+{
+	float4x4 projection;
+	float4x4 modelview;
+	float4 lightPos;
+};
+
+cbuffer ubo : register(b0)
+{
+	UBO ubo;
+};
+
+VSOutput main (VSInput input)
+{
+	VSOutput output = (VSOutput)0;
+	float4 eyePos = mul(ubo.modelview, float4(input.Pos.x, input.Pos.y, input.Pos.z, 1.0));
+	output.Pos = mul(ubo.projection, eyePos);
+	float4 pos = float4(input.Pos, 1.0);
+	float3 lPos = ubo.lightPos.xyz;
+	output.LightVec = lPos - pos.xyz;
+	output.ViewVec = -pos.xyz;
+	output.Normal = input.Normal;
+	return output;
+}