Fix PowerShell/PowerShell#15128

Because PowerShell launched from pwrshplugin.dll via WinRM doesn't have a console attached, the console codepage is not setup correctly due to how .NET works. This means that ANSI/Unicode characters are incorrectly represented. Manually validated using tree command and this encoded command:

PS> $cmd = {
>>     [Console]::Out.WriteLine('café')
>> }
PS> $encCommand = [Convert]::ToBase64String([Text.Encoding]::Unicode.GetBytes($cmd.ToString()))
PS> $s = New-PSSession . -ConfigurationName powershell.7
PS> Invoke-Command -Session $s { pwsh -encodedcommand $using:enccommand }
café