Visualize outdated model version on the new controller in 'juju status'

[Alex Lutay]

Hi,

This is UX improvement based on the real experience with Maksim Beliaev today.

The latest `juju status` indicates the outdated controller/model version using the yellow color if the new juju is available (juju 3.4+ AFAIK, at least 3.2+). TL;DR:

> > juju controllers
> Controller Model User Access Cloud/Region Models Nodes HA Version
> lxd* maksim admin superuser localhost/localhost 2 1 none 3.4.1 # 3.4.1 is yellow here
> microk8s lisbon admin superuser microk8s/localhost 2 - - 3.4.2 # 3.4.2 is white here

This is a very nice UX which help a lot!
This is request to improve it a bit further IF controller has been upgraded already AND the model is still old.
The each model owner should upgrade their models independently on ProdStack6 (when owners are ready).

Otherwise Maksim has requested IS team controller upgrade not seeing controller is already new.

Proposal:

> > juju status
> Model Controller Cloud/Region Version ...
> maksim lxd localhost/localhost 3.4.1 ... # print 3.4.1 in blue IF controller ls already new/3.4.2+

It will show model owners they can execute 'juju upgrade-model' anytime they are ready.

Tnx!