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/glsl/ssao/blur.frag

@@ -0,0 +1,25 @@
+#version 450
+
+layout (binding = 0) uniform sampler2D samplerSSAO;
+
+layout (location = 0) in vec2 inUV;
+
+layout (location = 0) out float outFragColor;
+
+void main() 
+{
+	const int blurRange = 2;
+	int n = 0;
+	vec2 texelSize = 1.0 / vec2(textureSize(samplerSSAO, 0));
+	float result = 0.0;
+	for (int x = -blurRange; x < blurRange; x++) 
+	{
+		for (int y = -blurRange; y < blurRange; y++) 
+		{
+			vec2 offset = vec2(float(x), float(y)) * texelSize;
+			result += texture(samplerSSAO, inUV + offset).r;
+			n++;
+		}
+	}
+	outFragColor = result / (float(n));
+}