Pool-API: Create administrative Level 1 endpoint

[nicoprow]

Currently, in our data model the postal addresses contain a field for setting the administrative level 1 value. We expect here an ISO norm region code to be entered. For this, we created earlier metadata endpoints in the Pool which have the path "api/catena/regions". For a user it is confusing to have two different terminologies for the same concept, on time being called administrative level 1 and at another place called region.

Therefore we should align the naming by introducing a new Pool Metadata endpoint and deprecating the old ones.

Tasks

• [x] Add Metadata GET Endpoint "api/catena/administrative-areas-level1" (POST is no longer needed)
• [x] Connect the new GET endpoint with the existing service logic and region DTOs
• [x] Mark the region endpoints as deprecated
• [x] Rename region in DTOs and properties

[nicoprow]

We should rename regions in the new endpoint with administrative level 1. Also: regionCode -> code regionName -> name