Highlight critical alert details on incidents
### Problem to solve
When triaging incidents, it should be easy for you to identify how long an alert has been open and how many times the event has fired. These details are often critical when determining customer impact and what your team needs to respond to right now. In 13.4, we have surfaced the alert start time, events count, and a link to the originating alert front and center in a highlight bar in GitLab incidents. This information is avilable on incidents that are promoted from alerts.
### Intended users
* [Devon (DevOps Engineer)](https://about.gitlab.com/handbook/marketing/product-marketing/roles-personas/#devon-devops-engineer)
* [Allison (Application Ops)](https://about.gitlab.com/handbook/marketing/product-marketing/roles-personas/#allison-application-ops)
### Proposal
Surface the alert start time, events count, and a link to the alert page in the highlight bar:

### Further details
This works supports the [Incident Management](https://about.gitlab.com/direction/monitor/debugging_and_health/incident_management/) direction.
### Permissions and Security
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* [ ] Add expected impact to members with no access (0)
* [ ] Add expected impact to Guest (10) members
* [ ] Add expected impact to Reporter (20) members
* [ ] Add expected impact to Developer (30) members
* [ ] Add expected impact to Maintainer (40) members
* [ ] Add expected impact to Owner (50) members -->
### Documentation
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### Availability & Testing
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### What does success look like, and how can we measure that?
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### What is the type of buyer?
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### Is this a cross-stage feature?
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### Links / references
Updated highlight bar visible in [this Figma file](https://www.figma.com/file/TJK1o8gAm59QXWRxrkeRaE/Add-priority-severity-to-incident-list-gitlab-com-and-229402?node-id=63%3A342)
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