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/pushdescriptors/cube.frag

@@ -0,0 +1,16 @@
+// Copyright 2020 Google LLC
+
+Texture2D textureColorMap : register(t2);
+SamplerState samplerColorMap : register(s2);
+
+struct VSOutput
+{
+[[vk::location(0)]] float3 Normal : NORMAL0;
+[[vk::location(1)]] float3 Color : COLOR0;
+[[vk::location(2)]] float2 UV : TEXCOORD0;
+};
+
+float4 main(VSOutput input) : SV_TARGET
+{
+	return textureColorMap.Sample(samplerColorMap, input.UV) * float4(input.Color, 1.0);
+}