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/computenbody/particle_integrate.comp

@@ -1,30 +0,0 @@
-#version 450
-
-struct Particle
-{
-	vec4 pos;
-	vec4 vel;
-};
-
-// Binding 0 : Position storage buffer
-layout(std140, binding = 0) buffer Pos 
-{
-   Particle particles[ ];
-};
-
-layout (local_size_x = 256) in;
-
-layout (binding = 1) uniform UBO 
-{
-	float deltaT;
-	int particleCount;
-} ubo;
-
-void main() 
-{
-	int index = int(gl_GlobalInvocationID);
-	vec4 position = particles[index].pos;
-	vec4 velocity = particles[index].vel;
-	position += ubo.deltaT * velocity;
-	particles[index].pos = position;
-}