fix(3643) add containerd-snapshotter support

[dillon-giacoppo]

Fix for: #3643

containerd snapshotter is an experimental feature https://github.com/docker/docs/blob/1da5f51da8a9c40c4318c8cec90b3939f0a25ca2/content/manuals/engine/storage/containerd.md that uses the containerd image store.

Using containerd offers multiple benefits, primarily multi-platform images and wasm container support.

When user containerd-snapshotter, rootfs points to the wrong directory leading to error in cadvisor:

manager.go:1116] Failed to create existing container: ... failed to identify the read-write layer ID for container "<CONTAINER_ID>". - open /rootfs/var/lib/docker/image/overlayfs/layerdb/mounts/<CONTAINER_ID>/mount-id: no such file or directory

This PR adds support for overlayfs driver and retrieves the root path from containerd spec directly. With this PR the containers can be loaded successfully:

[iwankgb]

I would be more than happy to give it a chance, but I am no longer able to merge PRs in cAdvisor.

[wolfspyre]

curious why this isn't merged?