Revisit DriverHelper

[Alister Scott]

Since we're using async and await now, we should revisit the DriverHelper class and do some cleanup of these functions

These are broadly used so we need to make sure we don't break anything in wp.com and jetpack e2e tests by changing these

We also rely on these for catching things like stale element exceptions so moving to await we should still be able to catch errors and retry within these functions