Add tracing spans in CRI image service and pull.go

Signed-off-by: Swagat Bora <sbora@amazon.com>

Add spans around image unpack operations
Use image.ref to denote image name and image.id for the image config digest
Add top-level spand and record errors in the CRI instrumentation service

pkg/cri/server/image_remove.go

@@ -22,6 +22,8 @@ import (
 
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/tracing"
+	"go.opentelemetry.io/otel/attribute"
 
 	runtime "k8s.io/cri-api/pkg/apis/runtime/v1"
 )
@@ -33,15 +35,17 @@ import (
 // Remove the whole image no matter the it's image id or reference. This is the
 // semantic defined in CRI now.
 func (c *criService) RemoveImage(ctx context.Context, r *runtime.RemoveImageRequest) (*runtime.RemoveImageResponse, error) {
+	span := tracing.CurrentSpan(ctx)
 	image, err := c.localResolve(r.GetImage().GetImage())
 	if err != nil {
 		if errdefs.IsNotFound(err) {
+			span.AddEvent(err.Error())
 			// return empty without error when image not found.
 			return &runtime.RemoveImageResponse{}, nil
 		}
 		return nil, fmt.Errorf("can not resolve %q locally: %w", r.GetImage().GetImage(), err)
 	}
-
+	span.SetAttributes(attribute.String("image.id", image.ID))
 	// Remove all image references.
 	for i, ref := range image.References {
 		var opts []images.DeleteOpt