Add link on PagerDuty incident pointing to the corresponding Backstage entity

[t1agob]

Is your feature request related to a problem? Please describe.
On PagerDuty, when an integration to Backstage is created, there is no easy way to navigate to that specific entity in Backstage directly.

Describe the solution you'd like
I would like to have a link that would allow me to easily navigate to the mapped Backstage entity from a PagerDuty incident. This can be a custom field with the type URL.

Describe alternatives you've considered
Currently I'm going to backstage and search for the service.

Additional context
This feature was requested by @brianphillips and the Shutterstock team.