(GraphicsAPI) Use spec consts to change shader local work group size

[cfnptr]

We can optimize shaders for a different thread warp sizes on Nvidia, AMD and other GPUs.

https://www.reddit.com/r/vulkan/comments/cabask/set_localsize_dynamically/

Workgroup size is local size, they're the same thing.

You set it "dynamically" via specialization constants. In your GLSL, declare instead

layout(local_size_x_id = 0, local_size_y = 1, local_size_z = 1)

then on pipeline creation, specify the desired value for spec constant location 0. This does mean that, > yes, you have to rebuild your pipeline every time you change the values.

[cfnptr]

Also use VkPhysicalDeviceSubgroupProperties.subgroupSize to detect the best local work group size.