Improvements around eject icon in context menu and side-pane

Version information

master / 4.19.3

Volumes which provide an "eject" button can have different actions bound to that action. See thunar_device_get_eject_label:

    switch (start_stop_type)
      {
      case G_DRIVE_START_STOP_TYPE_SHUTDOWN:
        return _("Safely _Remove");
      case G_DRIVE_START_STOP_TYPE_NETWORK:
        return _("_Disconnect");
      case G_DRIVE_START_STOP_TYPE_MULTIDISK:
        return _("Stop the _Multi-Disk Drive");
      case G_DRIVE_START_STOP_TYPE_PASSWORD:
        return _("_Lock");
      case G_DRIVE_START_STOP_TYPE_UNKNOWN:
      default:
        return _("_Eject");
      }

Currently, the shortcuts-side-pane show the same icon for all of these actions:

However, it would be much more convenient to ship a different icon for each of the start-stop-types. So:

1. Provide different "eject" icons per start-stop-type in the shortcuts-side-pane
2. Provide that icon as well in the right-click context menu
3. Provide a tooltip for the icon in the shortcuts-side-pane to make clear what the icon actually does