Initialize using apiKey string or Environment.get

[JaapWijnen]

Could we upgrade the initialize method to either receive a string instead of relying on it being in the environment, this way developers can choose their own environment name, but can also use a .env file if they want.
We can do something like:

public func initialize(apiKey: String) {            
   self.application.storage[Key.self] = .init(apiKey: apiKey)
}