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/pipelines/wireframe.frag

@@ -0,0 +1,6 @@
+// Copyright 2020 Google LLC
+
+float4 main([[vk::location(0)]] float3 Color : COLOR0) : SV_TARGET
+{
+	return float4(Color * 1.5, 1);
+}