[dataimport] introduce the importer and extentity classes This introduces the ``ExtEntity`` class which is a transitional state between data at external source and the actual CubicWeb entities. ``ExtEntitiesImporter`` is then in charge to turn a bunch of ext entities into CW entities in repository, using a given store. This changeset also introduces ``SimpleImportLog`` and ``HTMLImportLog`` which implement the CW DataImportLog interface in order to show log messages in UI using simple text and HTML formats respectively, instead of storing these messages in database. Both have mostly been backported from cubes.skos.dataimport. Closes #5414753.

from logilab.common.shellutils import generate_password
from cubicweb.server.utils import crypt_password

for user in rql('CWUser U WHERE U cw_source S, S name "system", U upassword P, U login L').entities():
    salt = user.upassword.getvalue()
    if crypt_password('', salt) == salt:
        passwd = generate_password()
        print 'setting random password for user %s' % user.login
        user.set_attributes(upassword=passwd)

commit()