container/docker: GetStats: prevent nil-pointer

stats can be nil if an error occurs during collecting

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

fix: handle nil Health state in docker container handler

Container.State.Health can be nil when no health check is configured.
Check for nil before accessing .Status to prevent panic.

Fixes nil pointer dereference in newDockerContainerHandler when
inspecting containers without health checks.

Signed-off-by: Davanum Srinivas <davanum@gmail.com>

Use built-in error wrapping instead of pkg/errors (#3689)

github.com/pkg/errors is archived and unmaintained; this replaces that
as follows:
* instead of extracting the cause for os.IsNotExist, use errors.Is
  directly (which unwraps errors itself)
* wrap errors using fmt.Errorf (wrapped errors using pkg/errors add
  the error message after a colon, so this changes the format to
  match)
* errors.Wrapf is replaced with fmt.Errorf

Signed-off-by: Stephen Kitt <skitt@redhat.com>
Co-authored-by: Davanum Srinivas <davanum@gmail.com>

Make resctrl optional/pluggable

Signed-off-by: Davanum Srinivas <davanum@gmail.com>

Merge pull request #3666 from dims/bump-to-newer-opencontainers/image…

…-spec-v1.1.1

Bump to newer opencontainers/image-spec @ v1.1.1

release v0.51.0