refactor: completely revamp the API design for the Helix client

[LosFarmosCTL]

Future requests will, instead of being called on the Helix instance itself, use HelixEndpoint objects with static factory methods for all the different endpoints, using generics to automatically infer return values:

// The old way
helix.doSomething(param1: "forsen")

// The new way
helix.request(endpoint: .doSomething(param1: "forsen"))

This allows the networking code to be separated properly from the code defining endpoints, therefore allowing different styles of network requests without having to write parts of them again for each endpoint.

// Completion Handlers
helix.requestTask(for: .doSomething(param1: "forsen")) { result, error in
}

// Async/Await
let result = try await helix.request(endpoint: .doSomething(param1: "forsen"))

// Combine
helix.requestPublisher(for: .doSomething(param1: "forsen")).sink(
  receiveCompletion: { error in

  },
  receiveValue: { result in

  })