Simulate "installation", "installation_repositories", "installation_target" events

By design, the webhook relay cannot subscribe to events that are only supported by apps, because under the hood manual repository hooks and organization hooks are used. See https://github.com/gr2m/github-webhook-relay/#how-it-works

However, we could simulate these events. At least for the `installation` and `installation_repositories` events, we could continuously request [the `GET /repos/{owner}/{repo}/installation` endpoint](https://docs.github.com/en/free-pro-team@latest/rest/apps/apps?apiVersion=2022-11-28#get-a-repository-installation-for-the-authenticated-app) and then emulate the events if an installation was added or removed. We could simulate the `installation_target` event at the same time and just make up the previous name of the owner.

Alternatively we could add a `.simulate()` method for these three events and all the other events that are only supported by GitHub apps:

- [github_app_authorization](https://docs.github.com/en/webhooks/webhook-events-and-payloads#github_app_authorization)
- [deployment_protection_rule](https://docs.github.com/en/webhooks/webhook-events-and-payloads#deployment_protection_rule)
- [deployment_review](https://docs.github.com/en/webhooks/webhook-events-and-payloads#deployment_review)
- [merge_group](https://docs.github.com/en/webhooks/webhook-events-and-payloads#merge_group)
- [personal_access_token_request](https://docs.github.com/en/webhooks/webhook-events-and-payloads#personal_access_token_request)
- [repository_dispatch](https://docs.github.com/en/webhooks/webhook-events-and-payloads#repository_dispatch)

And in some way also [ping](https://docs.github.com/en/webhooks/webhook-events-and-payloads#ping)