Add stack file and fix build

[TristanCacqueray]

This change adds a stack file to build the project with lts-11.22 and
a compatible vulkan-api version.

This change also fixes the defaultWindow record for VulkanContext and
update the shader path to be relative.

[TristanCacqueray]

Not sure if that is correct, the extra deps versions was picked randomly until the project built. In particular, I couldn't find the library that provided the SDL.windowVulkan defaultWindow constructor. This PR let me build and run the project using stack build.

[dpwiz]

I'm too using SDL.windowGraphicsContext = SDL.VulkanContext for this.

[dpwiz]

BTW, I can run it with LTS-14. Pushing into LTS-15 should require only minor tweaks here and there.

[ocharles]

Thanks for the feedback folks! I'm trying to keep all dev on this strictly on stream, and will leave the PR for that too. Maybe this is motivation to crack on with the project again! 😆

[TristanCacqueray]

Thank you for putting that project together @ocharles, it's very instructive. I find nix difficult to use for OpenGL outside of nixos, even with nixgl, thus having a cabal or stack build would be even better :-)