Load the current tick to a local variable, moving it out of an atomic
and allowing us to compare the value without going through a pointer
each time. This should make the loop more optimizable.
The "VK" prefix predates the "Vulkan" namespace. It was carried around
the codebase for consistency. "VKDevice" currently is a bad alias with
"VkDevice" (only an upcase character of difference) that can cause
confusion. Rename all instances of it.
This reworks how host<->device synchronization works on the Vulkan
backend. Instead of "protecting" resources with a fence and signalling
these as free when the fence is known to be signalled by the host GPU,
use timeline semaphores.
Vulkan timeline semaphores allow use to work on a subset of D3D12
fences. As far as we are concerned, timeline semaphores are a value set
by the host or the device that can be waited by either of them.
Taking advantange of this, we can have a monolithically increasing
atomic value for each submission to the graphics queue. Instead of
protecting resources with a fence, we simply store the current logical
tick (the atomic value stored in CPU memory). When we want to know if a
resource is free, it can be compared to the current GPU tick.
This greatly simplifies resource management code and the free status of
resources should have less false negatives.
To workaround bugs in validation layers, when these are attached there's
a thread waiting for timeline semaphores.
