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/deferred/debug.frag

@@ -0,0 +1,22 @@
+// Copyright 2020 Google LLC
+
+Texture2D texturePosition : register(t1);
+SamplerState samplerPosition : register(s1);
+Texture2D textureNormal : register(t2);
+SamplerState samplerNormal : register(s2);
+Texture2D textureAlbedo : register(t3);
+SamplerState samplerAlbedo : register(s3);
+
+float4 main([[vk::location(0)]] float3 inUV : TEXCOORD0) : SV_TARGET
+{
+	float3 components[3];
+	components[0] = texturePosition.Sample(samplerPosition, inUV.xy).rgb;
+	components[1] = textureNormal.Sample(samplerNormal, inUV.xy).rgb;
+	components[2] = textureAlbedo.Sample(samplerAlbedo, inUV.xy).rgb;
+	// Uncomment to display specular component
+	//components[2] = float3(textureAlbedo.Sample(samplerAlbedo, inUV.st).a);
+
+	// Select component depending on z coordinate of quad
+	int index = int(inUV.z);
+	return float4(components[index], 1);
+}