Add an email notification when a deployment is close to running out of funds

[baktun14]

Why

When the user has a deployment without auto top up and close to running out funds, we should warn the user.

What

Send an email when it's a couple hours away from closing

• Promote the auto top up and auto credit reload

[anilmurty]

would suggest making this a property on the generic deployment close alert with the deployment close reason (which core eng says is now accessible through an enum) indicated in the alert/ notification