TODOs APIs failing when todo's target_type is WorkItem

We've been getting this error in the TODO's REST API

This is due to the fact that some TODO target_types are WorkItem and not Issue. We need to add a WorkItem entity to the REST API.

This is also for the GraphQL API when fetching a target from the WorkItem type when the target is a work item

Edited Sep 23, 2022 by Mario Celi