Adds cri-dockerd initd service

[Nino-K]

This change adds the cri-dockerd service to initd. It needs clarification on creating and passing /etc/conf.d/cri-dockerd with the ENGINE type variable.

This PR bumps the Alpine ISO and WSL distro:
Fixes #1788

[mook-as]

Looks reasonable, just a syntax error.

[mook-as]

LGTM

[jandubois]

Maybe I misunderstand how this works, but it looks incomplete to me. It is my understanding that k3s will no longer support the --docker option, but instead you have to point the --container-runtime-endpoint to cri-dockerd, which in turn will point to docker.

This PR so far seems to still use --docker.

Since there is no official k3s-1.24 release yet (k8s 1.24 is scheduled for an April 19th release), the best way to test this for now would be to unconditionally use cri-dockerd instead of dockerd for all versions of k3s, and then we can test this against older releases.

[Nino-K]

@jandubois I enabled the cri-docker shim for all versions of k3s. I was under the assumption that we are going to do the final enabling once the --docker is deprecated in k3s. But enabling this for all k3s versions makes a lot of sense from a testing perspective.

[mook-as]

Seems to work on Windows & macOS.

I notice that it's using k8s.gcr.io/pause:3.1 instead of rancher/mirrored-pause:*. That corresponds to cri-dockerd --pod-infra-container-image=…. I'm not sure what the best way to get the desired image out of k3s is, though.

Approving, assume we can fix the pause thing in a separate issue — filed it as #1808

[jandubois]

LGTM, and tested with 1.16.14, 1.20.14, 1.23.3, and 1.24.0-alpha and seems to work fine with each.