The Vulkan Differences Between AMDGPU-PRO, RADV & SteamVR's RADV Drivers

With Valve having published a binary-only RADV Radeon Vulkan driver build for their beta of SteamVR on Linux, I did some poking out of curiosity to see the differences to the mainline RADV driver in Mesa. Out of curiosity I also did a comparison to see how the Vulkan capabilities compare to the proprietary AMDGPU-PRO Vulkan driver...