DSFE 4 - Apply new auth to FE

[AlexNi245]

After the completion of #824, the API changes have to be included to the FE.

• Use the new routes
• Handle new auth for BE and storage
• Implement challenge-response for expired tokens

[AlexNi245]

Implement the methods from lib http with the ones used in the connector.

• Look for deliveryServiceToken imports and remove methods imported there with the new one from the DeliveryServiceConnector
• Look for storageServiceToken imports and remove methods imported there with the new one from the/BackendConnector
• The BackendConnector is already completed, but the DeliveryServiceConnector might lack some methods from the old lib package. Add those methods like the others
• Migrate WS related files (Alex)

[AlexNi245]

Estimation: 3 days