Add HTML Support in the Notification Summary

[MikeAlhayek]

Is your feature request related to a problem? Please describe.

I need a way to be able to make notifications clickable on the UI. For example, I want to create a notification for when a content is published. When the user click on the notification, I want them to get redirected to the published content item. Currently there is no way of doing that since we use the property "Summary" as an email subject which can't contain HTML.

Describe the solution you'd like

Add a new property called Subject to the notifications object. The subject should not support HTML. However, the existsing Summary field should support HTML.