Fix ActorContext breakage due to get_api_models
Fix ActorContext breakage due to get_api_models

ActorContext is used in tests to make a functional test of an actor.
When the apis field for Actors was introduced, this has been overlooked.
This patch adds the missing changes for this part of the code.

Signed-off-by: Vinzenz Feenstra <600e8a10eeff4f08c65e2cf493cd851025e86fd2@redhat.com>

leapp-to/prototype,leapp-to/prototype,leapp-to/prototype,leapp-to/prototype