chore(providers) - decouple how provider can be registered in the system

@petrjasek  @ioanpocol feedback?
You are right but at this step the `ingest_providers` endpoint is not loaded yet. We either load the base endpoints for the app before this or we keep the current implementation. Probably we will have to have  a different registration mechanism for `users`, `auth` and `upload` anyway so `ingest_providers` will use the same.