Set $ProgressPreference to SilentlyContinue when using the powershell shell

Description

When using Windows Powershell the Invoke-WebRequest cmdlet is very slow: https://github.com/PowerShell/PowerShell/issues/13414

This can be fixed by either switching to Powershell Core or setting the $ProgressPreference preference variable to SilentlyContinue.

It also seems reasonable that the default should be that we don't show interactive progress when running in a CI pipeline.

Proposal

By default $ProgressPreference = 'SilentlyContinue' should be set when using the powershell shell. For consistency this should probably also be done for the pwsh shell.