Fix the launcher output window not decoding UTF-8 correctly

[hhyyrylainen]

When the launcher processes the log files those show up correctly but the output itself doesn't process UTF-8 characters properly. For example in this report: https://dev.revolutionarygamesstudio.com/reports/366

I already tried setting the encoding for the stdout of the ran processes in the common module we have, but that seemingly hasn't fixed the problem.