Lists all unsaved features in the current session. 
>>> customer_gender = catalog.get_view("GROCERYCUSTOMER")["Gender"].as_feature(
...     feature_name="Customer Gender"
... )
>>> fb.list_unsaved_features()[["variable_name", "name", "catalog", "active_catalog"]]
     variable_name             name  catalog  active_catalog
0  customer_gender  Customer Gender  grocery            True