Add support for configuring other integrations in the scaffolder

[t1agob]

Is your feature request related to a problem? Please describe.
Currently the PagerDuty plugin for Backstage provides a custom scaffolder action to create a PagerDuty service which creates the integration to PagerDuty but doesn't allow the configuration of other integrations.

Describe the solution you'd like
I would like to be able to select a list of integrations that I can setup directly from the project template (e.g. create GitHub integration so I can grab the Integration Key and use it in the software template as part of GitHub actions config to capture GitHub changes automatically).

This can be an additional step, or as part of the service creation step.

Describe alternatives you've considered
The is no way to do this from the plugin. These configurations need to be done as an additional step after the service is created.