Provisioning: introduce concept of provisioning extras (#104981)

* Spike: Extras

* Attempt to wire it up

* Hack

* Fix issue with jobs

* Wire more things up

* Fix more wiring stuff

* Remove webhook secret key from main registration

* Move secret encryption also outside register

* Add TODOs in code

* Add more explanations

* Move connectors to different package

* Move pull request job into webhooks

* Separate registration

* Remove duplicate files

* Fix missing function

* Extract webhook repository logic out of the core github repository

* Use status patcher in webhook connector

* Fix change in go mod

* Change hooks signature

* Remove TODOs

* Remove Webhook methos from go-git

* Remove leftover

* Fix mistake in OpenAPI spec

* Fix some tests

* Fix some issues

* Fix linting

pkg/registry/apis/provisioning/webhooks/pullrequest/testdata/update-dashboard.md

@@ -0,0 +1,9 @@
+Hey there! 🎉
+Grafana spotted some changes to your dashboard.
+### Side by Side Comparison of file.json
+| Before | After |
+|----------|---------|
+| ![Before](https://cdn2.thecatapi.com/images/99c.jpg) | ![Preview](https://cdn2.thecatapi.com/images/99c.jpg) |
+
+
+See the [original](http://grafana/d/uid) and [preview](http://grafana/admin/preview) of file.json.