Use QStringList::join(QChar) overload where applicable [examples]

Use QStringList::join(QChar) overload where applicable [examples]

This is an automated change performing the following replacements:
                    join\("(.)"\) -> join('\1')
  join\(QLatin1String\("(.)"\)\)  -> join(QLatin1Char('\1'))
  join\(QStringLiteral\("(.)"\)\) -> join(QLatin1Char('\1'))

Change-Id: I1d0c9782cc1522d937b930531720e32d4c8f7ce8
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>