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/subpasses/gbuffer.frag

@@ -1,36 +0,0 @@
-#version 450
-
-layout (location = 0) in vec3 inNormal;
-layout (location = 1) in vec3 inColor;
-layout (location = 2) in vec3 inWorldPos;
-
-layout (location = 0) out vec4 outColor;
-layout (location = 1) out vec4 outPosition;
-layout (location = 2) out vec4 outNormal;
-layout (location = 3) out vec4 outAlbedo;
-
-layout (constant_id = 0) const float NEAR_PLANE = 0.1f;
-layout (constant_id = 1) const float FAR_PLANE = 256.0f;
-
-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));	
-}
-
-void main() 
-{
-	outPosition = vec4(inWorldPos, 1.0);
-
-	vec3 N = normalize(inNormal);
-	N.y = -N.y;
-	outNormal = vec4(N, 1.0);
-
-	outAlbedo.rgb = inColor;
-
-	// Store linearized depth in alpha component
-	outPosition.a = linearDepth(gl_FragCoord.z);
-
-	// Write color attachments to avoid undefined behaviour (validation error)
-	outColor = vec4(0.0);
-}