Update Traffic Portal to account for new response/request structures for /deliveryservices/{{ID}}/servers

[ocket8888]

I'm submitting a ...

• new feature / enhancement request
• also kind of a prophecy of a bug that will exist in the future

Description

As soon as #4614 and/or #4615 is/are closed, the Traffic Portal functionality related to servers-to-Delivery Service assignments will be broken. It'll need to be updated to account for the new response/request structures.

This depends on #4614 and #4615 (and therefore #4611)

Traffic Control components affected ...

• Traffic Portal

Acceptance Criteria

• All Traffic Portal tests are passing
• Traffic Portal is capable of displaying, sorting, removing from and assigning to the list of servers assigned to a Delivery Service

See the Additional Server Interfaces blueprint for details.

[ocket8888]

This was resolved by #4747