Add --quiet to CLI

[isaacrlevin]

Based on #8377, it would be great to have the CLI quiet with specific commands, for example

$Env:Org = gh api /user | ConvertFrom-Json | Select-Object -ExpandProperty login
$ForkExists = gh api "/repos/$Env:Org/somereponame" | ConvertFrom-Json

if ($null -eq $ForkExists.id) {
    Write-Host "Forking the sample repository..."
    gh repo fork "someorg/somerepo" --default-branch-only --clone=false
}

If you run the above and the fork does not exist, you get the following message

gh: Not Found (HTTP 404)

It would be ideal if I could control the CLI that it didn't output anything, especially in this case as I might check this variable in the future. This would lead to a cleaner output which is nice in scripting scenarios.