rules: UDEV_DISABLE_PERSISTENT_STORAGE_RULES_FLAG property (#3714)

rules: UDEV_DISABLE_PERSISTENT_STORAGE_RULES_FLAG property (#3714)

Sometimes, the persistent storage rules should be skipped for a subset
of devices. For example, the Qubes operating system prevents dom0 from
parsing untrusted block device content (such as filesystem metadata) by
shipping a custom 60-persistent-storage.rules, patched to bail out early
if the device name matches a hardcoded pattern.

As a less brittle and more flexible alternative, this commit adds a line
to the two relevant .rules files which makes them test the value of the
UDEV_DISABLE_PERSISTENT_STORAGE_RULES_FLAG device property, modeled
after the various DM_UDEV_DISABLE_*_RULES_FLAG properties.