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/textoverlay/text.vert

@@ -0,0 +1,17 @@
+#version 450 core
+
+layout (location = 0) in vec2 inPos;
+layout (location = 1) in vec2 inUV;
+
+layout (location = 0) out vec2 outUV;
+
+out gl_PerVertex 
+{
+	vec4 gl_Position;   
+};
+
+void main(void)
+{
+	gl_Position = vec4(inPos, 0.0, 1.0);
+	outUV = inUV;
+}