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/inputattachments/attachmentread.vert

@@ -0,0 +1,10 @@
+#version 450
+
+out gl_PerVertex {
+	vec4 gl_Position;
+};
+
+void main() 
+{
+	gl_Position = vec4(vec2((gl_VertexIndex << 1) & 2, gl_VertexIndex & 2) * 2.0f - 1.0f, 0.0f, 1.0f);
+}