RFE: Add udev property to disable multipath merging

[grawity]

It would be great if I could mark certain devices via udev so that UDisks would never try to detect them as multipath devices.

For example, I have two identical USB drives, which for some reason have a bogus serial number, and as a result UDisks2 only recognizes the first device that was plugged in (it thinks it's a multipath device):

# udisksctl status
MODEL                     REVISION  SERIAL               DEVICE
--------------------------------------------------------------------------
TEAC TEAC FD-05PUW        0000      TEAC_TEAC_FD-05PUW   sdb sdc 

/org/freedesktop/UDisks2/drives/TEAC_TEAC_FD_05PUW_TEAC_TEAC_FD_05PUW:
  org.freedesktop.UDisks2.Drive:
    Id:                         TEAC-TEAC-FD-05PUW-TEAC_TEAC_FD-05PUW
    Media:                      floppy
    Model:                      TEAC FD-05PUW
    Serial:                     TEAC_TEAC_FD-05PUW
    SiblingId:                  /sys/devices/pci0000:00/0000:00:14.0/usb1/1-1/1-1:1.0
    Vendor:                     TEAC
    WWN:                        

This was discussed a bit in #490 and an udev property was proposed, but nothing was actually implemented (that I know of).

A similar situation was in #290 / #291, but those had different model numbers – meanwhile I have two same-model devices, so the devices still get merged.