Toggle Email Templates for Privacy and/or Increased Site Traffic

## Is your feature request related to a problem?
Right now, the email notifications seem to work quite well. This will be especially true after 8.1.0 allows for better subscription management.

In the meantime, the way that the forums communicate updates is not ideal for all scenarios. Currently, whenever there are updates, the update itself is sent to the inbox. If the person has nothing additional to add, they can just delete the email. This method of delivery has the following challenges:

- There isn't any incentive for email recipients to visit the website. This is a challenge for any website concerned about visits.
- In some cases, just putting the forum content into the email could be something that's flagged by security filters (and security certification processes).
- Changing the templates to not include the content is quite cumbersome and challenging for non-technical users.

## Describe the solution you'd like
We should have a second email template that only includes a CTA to come to the website to see what the update(s) is/are.

Assuming there is only a single update to view, they should be directed to that content, such as a forum reply.

If there are multiple updates, they should each be listed in the email - OR - a landing view could be implemented that displays all of the new content they're subscribed to, but not yet viewed.

In an administration view, someone that can edit the module should be able to toggle the email templates. The current templates should be the default since they're out there and this is already the default expected behavior. However, when toggled (checkbox?), the other email template that only has a link back to the content is sent out.

All email templates are treated the same way in terms of editing and deployment.

## Describe alternatives you've considered
None, yet.

## Additional context
Some certifications like FedRAMP don't allow content to be emailed to inboxes outside of the website.

Start by locating the current email notification templates and the administration view mentioned in the issue. Review how single and multiple updates are currently delivered, then define the template toggle behavior and verify that the existing templates remain the default while the link-only option is selectable.

Written by the indexing model from the issue text.