Pointer to a variable declared into a block statement is stored and used outside of the block by vkCreateInstance. This can lead to segmentation fault.
Move the declaration of validationExt/validationLayerName outside of the block to fix the crash.
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