[Uptime] Support email for simple monitor alerts

[justinkambic]

Is your feature request related to a problem? Please describe.
Today, users cannot set up an email connector for simple monitor alerts.

Describe the solution you'd like
We could add email as a connector for our simple alerts feature.

Describe alternatives you've considered
N/A

Additional context
We currently don't do this because we lack the necessary field definitions to define this connector. There may be additional, potentially blocking, challenges that are not detailed in this issue, so further investigation may be required.

Success criteria for this work would be an Email connector defined in the following screen, that users could then use to send alerts via the simple alerts rule: