Returns a specification to start this module under a supervisor.

See Supervisor.

@spec count_workers(module()) :: non_neg_integer()

Returns the number of active onboarding workers for an instance.

@spec get_or_start_worker(module(), String.t(), keyword()) ::
  {:ok, pid()} | {:error, term()}

Returns the worker for an onboarding flow, starting it when necessary.

@spec start_link(keyword()) :: Supervisor.on_start()

Starts the dynamic supervisor for onboarding workers.

@spec start_worker(module(), String.t(), keyword()) :: {:ok, pid()} | {:error, term()}

Starts or returns the worker for an onboarding flow.

@spec supervisor_name(module()) :: atom()

Resolves the registered supervisor name for an instance module.