Create NIX flake to build rayx for Linux

[ichinii]

In order to improve reliability and duration of builds in github CI we want to create a docker image, generated from a NIX flake.

the NIX flake should create a docker image that already contains layers for:

• Git
• Vulkan, shaderc
• Cuda
• HDF5
• build dependencies (cmake, gcc, ninja)
• valgrind

the execution of the docker image should do the following steps:

1. clone rayx
2. update submodules
3. generate build files (cmake)
4. build release (ninja)
5. perform tests
   • rayx-core-tst
   • valgrind rayx METRIX
6. copy data, scripts and include directories to output dir
7. what to do with external dependencies (HDF5)?

also consider

• can we create a nix package from here, that depends on our dependencies (HDF5)?
• what about other package managers (snap, pacman)?