Add support for multithreading

[SaschaWillems]

Explore the various constraints and benefits multithreading can bring to a Vulkan renderer, both ‘parallel’ and ‘concurrent’. Parallel work includes: Command buffer recording & pipeline creation. Concurrent work includes: Async asset uploading, kicking work off and checking in on it later.
Reason: Big benefit of vulkan is multithreading. Many see how parallel command buffer recording can be a benefit, less visibility on the async nature of vulkan.

Dependencies: Command buffer recording + Possibly delay delete queue

Note: Copied from the old repo's project board