Add build timestamp to Image status

[mailprak]

The kp image list currently shows :

kp image list -n
NAME READY LATEST REASON LATEST IMAGE NAMESPACE

Can the TIMESTAMP also be added as a field as below :
NAME READY LATEST REASON LATEST IMAGE NAMESPACE TIMESTAMP

Reason :
For troubleshooting :
Information on when the build of the Image happened.
The timestamp information can be correlated with when a rebase/rebuild of a image was triggered or re-triggered.

[chenbh]

This could work, but it'll require a change on the kpack controller's side. The build reconciler would need to update the ImageStatus to include the latest build start timestamp.

[chenbh]

We don't have any plans to work on this atm, but will welcome and PRs for the changes on both the controller and CLI side