Add support for devices in swarm

[zikaeroh]

- What I did

This is for:

• Add support for devices with "service create" moby/swarmkit#1244
• Proposal: Device Support moby/swarmkit#2682, though this PR series takes a much simpler approach.
• Unable to add devices with "service create" moby/moby#24865

This simply plumbs devices through everything such that swarm can specify the devices field.

- How I did it

Largely based on:

• Add Ulimits to ContainerSpec moby/swarmkit#2967
• Support ulimits on Swarm services. moby/moby#41284
• Add ulimits support to docker service and docker stack deploy (carry 2660) #2712

But, plumbing devices instead of ulimits.

This needs moby/swarmkit#3106 and moby/moby#44695.

- How to test it

Still working on this; I'm finding it pretty difficult to get all of the pieces set up.

- Description for the changelog

Add support for devices in swarm mode.

[zikaeroh]

This version is almost assuredly wrong. No idea if this should be 1.41, 1.42, or 1.43. I wasn't easily able to figure out what the current version is.

[vvoland]

Currently, the master's API version is 1.43: https://github.com/moby/moby/blob/master/api/common.go#L6

[thaJeztah]

I wonder if we should consider adding type=device to the mounts API; the --device option uses the shorthand (<device>:<target>) format, which is known to have caused issues; using the mounts API also allows for more flexibility (options specific to devices); I seem to recall there was a discussion somewhere in https://github.com/moby/moby about this, but I can't find it right now (will do some more searching).

With that approach, a device would be added (from a UX endpoint); would use the --mount syntax, which would look something like;

--mount type=device,src=/dev/sdc.target=/dev/xvdc

Additional options that are specific to a device can (in future) be added to those (e.g. some of the constraints)

[zikaeroh]

It's been a long time since I sent this PR chain. I'm sorry to say I just don't have the bandwidth to try and push this idea forward anymore; I'm going to close them.

These PRs (moby/swarmkit#3106, moby/moby#44695, #3930) are pretty straightforward, so I think anyone could re-propose the same changes (by all means, take the code, no need to credit me in any form). I just don't want to mislead anyone into thinking these PRs are likely to go in (at least without more investment).