Improve `att push` output

[migmartri]

now, att push supports both -o json and regular view. This task is about improving the default output to show something similar we show in our labs trust report

https://github.com/chainloop-dev/chainloop/actions/runs/8938087539#summary-24551614195

I believe that that output is the status of the attestation right before pushing it. We should also show the digest of the pushed att and maybe the duration.

[migmartri]

as I follow up for this, we should make sure that the labs repository keeps working. We have some functions there that create reports and links based on the output.

We would need to migrate those scripts to use the json output instead.