Use `az upgrade` in quiet mode

**Is your feature request related to a problem? Please describe.**
I'd like to use `az upgrade` without the need of human intervention on Windows.
Currently, running `az upgrade -y --all` still prompts a dialog where you have to accept license and click on next.

**Describe the solution you'd like**
`az upgrade --yes --all --quiet` upgrades all the az cli quietly, without any dialog or human interaction.

**Describe alternatives you've considered**
~~`Invoke-WebRequest -Uri https://aka.ms/installazurecliwindows -OutFile .\AzureCLI.msi; Start-Process msiexec.exe -Wait -ArgumentList '/I AzureCLI.msi /quiet'; rm .\AzureCLI.msi` would be doable, but it is way less elegant, and not cross platform.~~ Scratch that, I just tried and it doesn't work for updating from 2.16.0 to 2.18.0.