Add support for proxies

[rick-bennett]

There doesn't seem to be an existing method to configure the proxy settings. For those with devices behind firewalls, this would be a helpful enhancement to have (included before the initial sync).

$config = (Get-WsusServer).GetConfiguration()
$config.ProxyName = ${proxy_name}
$config.ProxyServerPort = ${proxy_port}
$config.UseProxy = $true
$config.Save()

[TraGicCode]

Hey @RFBennet ,

would you be able to submit a PR with this added feature?