* CLDC-4044: Reset last_sign_at fields on reactivation
this is to ensure that the code considers them a fresh user
specifically, ensures that the "Resend invite link" button will show
* CLDC-4044: Allow sending activation emails for unconfirmed users that have logged in
looks like CORE treats this state functionally for reconfirmed users & has a unique email sent out
so instead, change code to account for this and allow for sending emails to unconfirmed but signed in users
* CLDC-4044: Add verifying test
* CLDC-4044: Add clarifying comment