[transaction] move RQLRewriter in Transaction
This remove the last ``AttributeError`` magic. The ``RQLRewriter`` needs a Session. Its
reset is handled in ``Session`` code to handle that
change_attribute_type('CWCache', 'timestamp', 'TZDatetime')
change_attribute_type('CWUser', 'last_login_time', 'TZDatetime')
change_attribute_type('CWSource', 'latest_retrieval', 'TZDatetime')
drop_attribute('CWSource', 'synchronizing')
add_attribute('CWSource', 'in_synchronization')