Add Vulkan

[rossant]

Please see the repo readme for directions on how to make PRs on this repo.

Checklist:

• [X] if you have added a CDT, it appears in the cdt_slugs.yaml file and you have rerun the script python gen_cdt_recipes.py.
• [X] if you see a warning about a CDT not having a license, you have added the license_file key in the cdt_slugs.yaml file with the path to the appropriate license in licenses/

NOTE: If you make any changes to cd_slugs.yaml, you need to reun the generator code via python gen_cdt_recipes.py.

[rossant]

I need to make a conda-forge recipe for a C library that uses Vulkan. What's the best course of action, should I first make a conda-forge recipe for the Vulkan ICD loader, then add it as a build requirement to the C library (compilation of which requires vulkan.h)?

[isuruf]

Yes or you could add both in the same PR