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/multiview/viewdisplay.frag

@@ -0,0 +1,25 @@
+// Copyright 2020 Google LLC
+
+Texture2DArray textureView : register(t1);
+SamplerState samplerView : register(s1);
+
+struct UBO
+{
+	[[vk::offset(272)]] float distortionAlpha;
+};
+
+cbuffer ubo : register(b0) { UBO ubo; }
+
+[[vk::constant_id(0)]] const float VIEW_LAYER = 0.0f;
+
+float4 main([[vk::location(0)]] float2 inUV : TEXCOORD0) : SV_TARGET
+{
+	const float alpha = ubo.distortionAlpha;
+
+	float2 p1 = float2(2.0 * inUV - 1.0);
+	float2 p2 = p1 / (1.0 - alpha * length(p1));
+	p2 = (p2 + 1.0) * 0.5;
+
+	bool inside = ((p2.x >= 0.0) && (p2.x <= 1.0) && (p2.y >= 0.0 ) && (p2.y <= 1.0));
+	return inside ? textureView.Sample(samplerView, float3(p2, VIEW_LAYER)) : float4(0.0, 0.0, 0.0, 0.0);
+}