Lightning: Output a structural result at the end of lightning import

[cyliu0]

Feature Request

Describe your feature request related problem:

For test automation, it's hard to read the lightning import result(import duration, checksum duration) from the logs.

Describe the feature you'd like:

I'd like a structural result including lightning import result data at the end of lightning import. It would be nice if it's json. But text table or any other format which is easy to read for automation case would work too.

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy: