Add MBSF CRUD integration test

[ErikGaida]

Summary

Adds a pytest-based end-to-end CRUD test for the MBS Function APIs, following the MBSF Operations & APIs tutorial.

The test covers the two main Nmb10 resource types:

• MBS User Service
• MBS User Data Ingest Session

Coverage

MBS User Service

• Create an MBS User Service with POST
• Update its service description with PUT
• Retrieve it with GET
• Delete it with DELETE

MBS User Data Ingest Session

• Create a separate MBS User Service for the ingest-session flow
• Create a STREAMING / PULL MBS User Data Ingest Session with POST
• Update its distribution-session state from INACTIVE to ACTIVE with PUT
• Retrieve the updated session with GET
• Delete the ingest session with DELETE