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/hlsl/computeheadless/headless.comp

@@ -0,0 +1,28 @@
+// Copyright 2020 Google LLC
+
+RWStructuredBuffer<uint> values : register(u0);
+[[vk::constant_id(0)]] const uint BUFFER_ELEMENTS = 32;
+
+uint fibonacci(uint n) {
+	if(n <= 1){
+		return n;
+	}
+	uint curr = 1;
+	uint prev = 1;
+	for(uint i = 2; i < n; ++i) {
+		uint temp = curr;
+		curr += prev;
+		prev = temp;
+	}
+	return curr;
+}
+
+[numthreads(1, 1, 1)]
+void main(uint3 GlobalInvocationID : SV_DispatchThreadID)
+{
+	uint index = GlobalInvocationID.x;
+	if (index >= BUFFER_ELEMENTS)
+		return;
+	values[index] = fibonacci(values[index]);
+}
+