Feature Request

• Yes, I reviewed the contribution guidelines.

Describe your use case and the problem you are facing

wp plugin list --update=available fails to display what version updates are available.

Describe the solution you'd like

wp plugin list --update=available --fields=name,status,update,version,update_version works as desired, which made me wonder why update_version field isn't part of the default output set?

I am aware of update_version possibly being subject to a race condition, where a plugin author may upload a newer version during the time to user executing the actual wp plugin update command. Still feels like seeing update_version has more benefits than drawbacks.

Your thoughts?