Prepopulate resource notify emails field with GHC_NOTIFICATIONS_EMAILS

[Dukestep]

On an individual resource page, a user cannot see the GHC_NOTIFICATIONS_EMAILS that a notification will be sent to.

Solution

On resource creation, only the current logged in users email is prepopulated in the Notify emails field.

It would make sense to also populate it with the email values in GHC_NOTIFICATIONS_EMAILS since these addresses are also notified on a probe/check failure. It would also allow to "opt-out" certain email addresses from receiving a notification at the resource-level even although the address is in GHC_NOTIFICATIONS_EMAILS by simple removing the address from list.

Notifications would then only be sent for a resource to email address included in this field.

Alternatively, it would be useful to see at the resource level which global email addresses the notification email will be sent to in case of a probe/check fail. This could be an uneditable field.

CC @alexandreleroux