containerd integration: image save/load should produce a JSON stream and image events

[thaJeztah]

Description

• relates to containerd integration: Implement load/save #43822

The existing (non-containerd) implementation writes to a progress stream when loading images; this is currently missing in the containerd implementation; e.g.;

moby/image/tarexport/load.go

Line 132 in 7e8df0e

outStream.Write([]byte(fmt.Sprintf("Loaded image: %s\n", reference.FamiliarString(ref))))

moby/image/tarexport/load.go

Line 149 in 7e8df0e

outStream.Write([]byte(imageIDsStr))

In addition, the existing implementation generates "image load" and "image save" events;

moby/image/tarexport/load.go

Line 137 in 7e8df0e

l.loggerImgEvent.LogImageEvent(imgID.String(), imgID.String(), "load")

moby/image/tarexport/save.go

Line 227 in 7e8df0e

s.tarexporter.loggerImgEvent.LogImageEvent(id.String(), id.String(), "save")

[vvoland]

Reopening this one as this was only partially addressed.
Image events are produced, but JSON stream with progress is still missing.