WIP: Vulkan support | Part 2 - simple objects

This PR depends on !14 (closed) and !21 (closed) (First 4 commits should be ignored)

This PR adds simple Vulkan objects creation. Vtest is supposed to change soon, so I dropped this part for now.

Each VkDevice instance on the host is linked to a hashtable containing all objects related to it. (Similar to a VGL context)

The few objects involved are the one needed to run the basic compute example (https://github.com/Keenuts/vulkan-compute)