Expose addressing mode as a device attribute

[elezar]

Some systems have GPUs which have full access to system memory and others which do not. Furthermore, there are applications that can only run on one or the other. In order for users to select the "correct" type of GPU for their workload, we should expose a device's addressing mode as an attribute for selection.

See also NVIDIA/nvidia-container-toolkit#1247 (comment)

Note that this PR adds the concept of coherence, but this was found to insufficiently defined and the distinction was removed. It may still be desireable to expose the addressing mode since an application developer could then define cel expressions based on this.

[klueska]

Are there helpers in go-nvlib that I can call to tell me if a GPU is coherent or not?
What do you think the attribute should look like?
I'm thinking a boolean coherent = true | false.

[elezar]

An IsCoherent helper was added in NVIDIA/go-nvlib#68. We are treating this as binary for container-toolkit use cases, so I think a boolean would make sense.