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/ssao/gbuffer.frag

@@ -0,0 +1,34 @@
+// Copyright 2020 Google LLC
+
+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;
+};
+
+struct FSOutput
+{
+	float4 Position : SV_TARGET0;
+	float4 Normal : SV_TARGET1;
+	float4 Albedo : SV_TARGET2;
+};
+static const float NEAR_PLANE = 0.1f; //todo: specialization const
+static const float FAR_PLANE = 64.0f; //todo: specialization const
+
+float linearDepth(float depth)
+{
+	float z = depth * 2.0f - 1.0f;
+	return (2.0f * NEAR_PLANE * FAR_PLANE) / (FAR_PLANE + NEAR_PLANE - z * (FAR_PLANE - NEAR_PLANE));
+}
+
+FSOutput main(VSOutput input)
+{
+	FSOutput output = (FSOutput)0;
+	output.Position = float4(input.WorldPos, linearDepth(input.Pos.z));
+	output.Normal = float4(normalize(input.Normal) * 0.5 + 0.5, 1.0);
+	output.Albedo = float4(input.Color * 2.0, 1.0);
+	return output;
+}