additional actions/links to be renderd in PagerDuty sink and leverage links parameters

[zmx]

Is your feature request related to a problem?
The use case is as same as #814 , but leverage links parameters in https://developer.pagerduty.com/docs/ZG9jOjExMDI5NTgx-send-an-alert-event#parameters

We links to Runbook/Grafana/Loki with templating labels/annotations

Describe the solution you'd like
Passing additional (external) links to the (pagerduty_)sink configs which are then rendered when present on the alert.

Describe alternatives you've considered
Currently we use template_enricher as alternative

Additional context
Add any other context or screenshots about the feature request here.