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/base/uioverlay.vert

@@ -0,0 +1,25 @@
+#version 450
+
+layout (location = 0) in vec2 inPos;
+layout (location = 1) in vec2 inUV;
+layout (location = 2) in vec4 inColor;
+
+layout (push_constant) uniform PushConstants {
+	vec2 scale;
+	vec2 translate;
+} pushConstants;
+
+layout (location = 0) out vec2 outUV;
+layout (location = 1) out vec4 outColor;
+
+out gl_PerVertex 
+{
+	vec4 gl_Position;   
+};
+
+void main() 
+{
+	outUV = inUV;
+	outColor = inColor;
+	gl_Position = vec4(inPos * pushConstants.scale + pushConstants.translate, 0.0, 1.0);
+}