windows: set text encodig for powershell to utf-8

by default powershell uses the OEM-US/codepage 437
encoding which is an extension of ASCII

when a character with umlaut is used and powershell
uses the default encoding go is unable to  properly
convert it to a go string as it doesn't  understand
the OEM-US encoding by default and replaces it with
'U+FFFD' and we get a ? in the output

the preflight check, checking if  username in group
fails since the username is not correct because  of
the '?' character in it, this fixes it by using the
utf-8 encoding for powershell

pkg/os/windows/powershell/powershell_windows.go

@@ -36,7 +36,8 @@ func Execute(args ...string) (string, string, error) {
 	if err != nil {
 		return "", "", err
 	}
-	args = append([]string{"-NoProfile", "-NonInteractive", "-ExecutionPolicy", "RemoteSigned", "-Command", "$ProgressPreference = 'SilentlyContinue';"}, args...)
+	args = append([]string{"-NoProfile", "-NonInteractive", "-ExecutionPolicy", "RemoteSigned", "-Command",
+		"$ProgressPreference = 'SilentlyContinue';", "[Console]::OutputEncoding = [System.Text.UTF8Encoding]::new();"}, args...)
 	cmd := exec.Command(powershell, args...) // #nosec G204
 	cmd.SysProcAttr = &syscall.SysProcAttr{HideWindow: true}
 
@@ -85,6 +86,7 @@ func ExecuteAsAdmin(reason, cmd string) (string, string, error) {
 
 func runAsCmds(powershell string) []string {
 	return []string{
+		`[Console]::OutputEncoding = [System.Text.UTF8Encoding]::new();`,
 		`$myWindowsID = [System.Security.Principal.WindowsIdentity]::GetCurrent();`,
 		`$myWindowsPrincipal = New-Object System.Security.Principal.WindowsPrincipal($myWindowsID);`,
 		`$adminRole = [System.Security.Principal.WindowsBuiltInRole]::Administrator;`,