Deployments: Open-source version of POST /device/deployments/next

As part of the 4th iteration of Artifact Depends and Provides epic, a new POST version of the /device/deployments/next endpoint was created in order to pass provides parameters in the request body. This implies changing the request check update method to POST for the client with a fallback to the previous GET method. In order not to trigger this fallback logic on every poll interval, a POST /next endpoint in the opensource discarding all additional provides parameters is needed.

Acceptance criteria:

• Create endpoint for: POST /device/deployments/next
  • Endpoint behaves exactly like the GET counterpart except the query parameters are moved to the body.