Move shaders into glsl and hlsl directories

Move `data/shaders` to `data/shaders/glsl`
Move `data/hlsl` to `data/shaders/hlsl`

Fix up shader paths in the cpp files to point to the new glsl location.

`data/shaders/hlsl/compile.py` still overwrites the glsl .spv files (for
now).

Issue: #723

data/shaders/hlsl/pushconstants/lights.frag

@@ -0,0 +1,37 @@
+// Copyright 2020 Google LLC
+
+#define lightCount 6
+
+struct VSOutput
+{
+[[vk::location(0)]] float3 Normal : NORMAL0;
+[[vk::location(2)]] float3 Color : COLOR0;
+[[vk::location(3)]] float4 LightVec[lightCount] : TEXCOORD1;
+};
+
+#define MAX_LIGHT_DIST 9.0 * 9.0
+
+float4 main(VSOutput input) : SV_TARGET
+{
+	float3 lightColor[lightCount];
+	lightColor[0] = float3(1.0, 0.0, 0.0);
+	lightColor[1] = float3(0.0, 1.0, 0.0);
+	lightColor[2] = float3(0.0, 0.0, 1.0);
+	lightColor[3] = float3(1.0, 0.0, 1.0);
+	lightColor[4] = float3(0.0, 1.0, 1.0);
+	lightColor[5] = float3(1.0, 1.0, 0.0);
+
+	float3 diffuse = float3(0.0, 0.0, 0.0);
+	// Just some very basic attenuation
+	for (int i = 0; i < lightCount; ++i)
+	{
+		float lRadius =  MAX_LIGHT_DIST * input.LightVec[i].w;
+
+		float dist = min(dot(input.LightVec[i], input.LightVec[i]), lRadius) / lRadius;
+		float distFactor = 1.0 - dist;
+
+		diffuse += lightColor[i] * distFactor;
+	}
+
+	return float4(diffuse, 1);
+}

data/shaders/hlsl/pushconstants/lights.vert

@@ -0,0 +1,50 @@
+// Copyright 2020 Google LLC
+
+struct VSInput
+{
+[[vk::location(0)]] float3 Pos : POSITION0;
+[[vk::location(1)]] float3 Normal : NORMAL0;
+[[vk::location(3)]] float3 Color : COLOR0;
+};
+
+#define lightCount 6
+
+struct UBO
+{
+	float4x4 projection;
+	float4x4 model;
+	float4 lightColor[lightCount];
+};
+
+cbuffer ubo : register(b0) { UBO ubo; }
+
+struct PushConsts {
+	float4 lightPos[lightCount];
+};
+[[vk::push_constant]] PushConsts pushConsts;
+
+struct VSOutput
+{
+	float4 Pos : SV_POSITION;
+[[vk::location(0)]] float3 Normal : NORMAL0;
+[[vk::location(2)]] float3 Color : COLOR0;
+[[vk::location(3)]] float4 LightVec[lightCount] : TEXCOORD1;
+};
+
+VSOutput main(VSInput input)
+{
+	VSOutput output = (VSOutput)0;
+	output.Normal = input.Normal;
+	output.Color = input.Color;
+
+	output.Pos = mul(ubo.projection, mul(ubo.model, float4(input.Pos.xyz, 1.0)));
+
+	for (int i = 0; i < lightCount; ++i)
+	{
+		float4 worldPos = mul(ubo.model, float4(input.Pos.xyz, 1.0));
+		output.LightVec[i].xyz = pushConsts.lightPos[i].xyz - input.Pos.xyz;
+		// Store light radius in w
+		output.LightVec[i].w = pushConsts.lightPos[i].w;
+	}
+	return output;
+}