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/bloom/skybox.vert

@@ -0,0 +1,22 @@
+// Copyright 2020 Google LLC
+
+cbuffer UBO : register(b0)
+{
+	float4x4 projection;
+	float4x4 view;
+	float4x4 model;
+};
+
+struct VSOutput
+{
+	float4 Pos : SV_POSITION;
+	[[vk::location(0)]] float3 UVW : NORMAL0;
+};
+
+VSOutput main([[vk::location(0)]] float3 inPos : POSITION0)
+{
+	VSOutput output = (VSOutput)0;
+	output.UVW = inPos;
+	output.Pos = mul(projection, mul(view, mul(model, float4(inPos.xyz, 1.0))));
+	return output;
+}