Add hooks on generateHistoricalMetrics

[Symbolic76]

I've been trying to mock API calls to be able to cancel requests from generateHistoricalMetrics.

I realized there is no hooks on this method and i can't mock this properly.

[wcoots]

@Symbolic76 Interesting idea, this would involve creating a generic hook for all service methods with the method called being passed as an argument (or perhaps just the name of the function). We will consider this for the next version of the API.