[REG 5.13 -> 5.14] QtWebEngine is listed as "Chromium" in PulseAudio

As seen in e.g. pavucontrol, or here:

» pacmd list-sink-inputs | grep Chromium
    client: 311 <Chromium>
        application.name = "Chromium"
        module-stream-restore.id = "sink-input-by-application-name:Chromium"

This can likely be fixed by calling AudioManager::SetGlobalAppName() (related Chromium change) to pass the QCoreApplication::applicationName() to it.

This is a clone of QTBUG-67707 - looks like https://codereview.qt-project.org/#/c/226343/ stopped working with Qt 5.14.