Add detector for docker container id for cgroup v2 to be added to resource metadata

[svrnm]

Is your feature request related to a problem? Please describe

Detection of the container.id via @opentelemetry/resource-detector-docker currently works by reading from /proc/self/cgroup. That does not work when cgroupv2 is turned on. However, based on these two sources there's another place to read from:

• How to get docker container ID from within the container with cgroup v2
• Python NullResource error when running torizoncore-builder build

In short, the container.id could be read from /proc/self/mountinfo as well. This also works for containerd and not only docker.

Eventually it would be good to have a standard for that, but unfortunately this is a long-standing non-moving OCI issue, until then a combination of both approaches seems to be reliable enough.

Describe the solution you'd like to see

Add code that reads the container id from /proc/self/mountinfo if reading from /proc/self/cgroup failed.

Describe alternatives you've considered

As stated in the description, eventually it would be great to have this standardized, but until then this is the best way to go.

cc: @abhee11, @osherv

[abhee11]

Please assign this to me - I will have a PR ready by eod today or tomorrow

[github-actions]

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 14 days.

[svrnm]

Closed via #1181