The e-mail validator now requires a domain.
Switching from 'withGoogle' to 'withInsights' now sets the other GCP
related options to 'undefined' in order to keep the store state such
that it accurately reflects the current wizard state.
This is done in the reducer, not via a listener. That is a bit
inconsistent with the current listeners in place but this is an evolving
design and the inconsistency is acceptable for now. We may either accept
it, move the reducer actions here into listeners, or move the existing
listeners into reducers at some point in the future.
