cri: support blockio class in pod and container annotations

This patch adds support for a container annotation and two separate
pod annotations for controlling the blockio class of containers.

The container annotation can be used by a CRI client:
  "io.kubernetes.cri.blockio-class"

Pod annotations specify the blockio class in the K8s pod spec level:
  "blockio.resources.beta.kubernetes.io/pod"
  (pod-wide default for all containers within)

  "blockio.resources.beta.kubernetes.io/container.<container_name>"
  (container-specific overrides)

Correspondingly, this patch adds support for --blockio-class and
--blockio-config-file to ctr, too.

This implementation follows the resource class annotation pattern
introduced in RDT and merged in commit 893701220.

Signed-off-by: Antti Kervinen <antti.kervinen@intel.com>

oci/spec_opts_linux.go

@@ -84,6 +84,15 @@ func WithPidsLimit(limit int64) SpecOpts {
 	}
 }
 
+// WithBlockIO sets the container's blkio parameters
+func WithBlockIO(blockio *specs.LinuxBlockIO) SpecOpts {
+	return func(ctx context.Context, _ Client, c *containers.Container, s *Spec) error {
+		setResources(s)
+		s.Linux.Resources.BlockIO = blockio
+		return nil
+	}
+}
+
 // WithCPUShares sets the container's cpu shares
 func WithCPUShares(shares uint64) SpecOpts {
 	return func(ctx context.Context, _ Client, c *containers.Container, s *Spec) error {

oci/spec_opts_nonlinux.go

@@ -39,6 +39,14 @@ var WithAllKnownCapabilities = func(ctx context.Context, client Client, c *conta
 	return WithCapabilities(nil)(ctx, client, c, s)
 }
 
+// WithBlockIO sets the container's blkio parameters
+//nolint: deadcode, unused
+func WithBlockIO(blockio interface{}) SpecOpts {
+	return func(ctx context.Context, _ Client, c *containers.Container, s *Spec) error {
+		return errors.New("blkio not supported")
+	}
+}
+
 // WithCPUShares sets the container's cpu shares
 //nolint: deadcode, unused
 func WithCPUShares(shares uint64) SpecOpts {