When deleting prints, the API user should also delete the print from the
storage (for devices that support on-device storage). Add an example to
show how to do this.
This is useful as these devices may require extra work by API users,
such as also deleting prints from the device when deleting them from
the local storage.
Some new fingerprint devices store the information required for matching
on the sensor itself, without ever disclosing this data to the host. In
this case we need to delete prints not only from local storage but also
from the device storage.
This commits adds the internal and external API required to do so.
