how i tested the `SET_ACCESS_TOKEN` action: https://gist.github.com/vdhanan/c1a70adc6125268a8f9a085f0b1fcea2
tested the other cases in `reduceServicesAccessToken` by logging out and deleting account on iOS simulator and dispatching a `SET_NEW_SESSION` action manually from the redux devtools (confirmed that the token was set to null in redux state in all these cases)