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/deferredshadows/debug.frag

@@ -1,26 +0,0 @@
-#version 450
-
-layout (binding = 1) uniform sampler2D samplerPosition;
-layout (binding = 2) uniform sampler2D samplerNormal;
-layout (binding = 3) uniform sampler2D samplerAlbedo;
-layout (binding = 5) uniform sampler2DArray samplerDepth;
-
-layout (location = 0) in vec3 inUV;
-
-layout (location = 0) out vec4 outFragColor;
-
-float LinearizeDepth(float depth)
-{
-  float n = 0.1; // camera z near
-  float f = 64.0; // camera z far
-  float z = depth;
-  return (2.0 * n) / (f + n - z * (f - n));	
-}
-
-void main() 
-{
-	// Display depth from light's point-of-view 
-	// inUV.w = number of light source
-	float depth = texture(samplerDepth, vec3(inUV)).r;
-	outFragColor = vec4(vec3(1.0 - LinearizeDepth(depth)), 0.0);
-}