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

[gr2m]

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 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
• deployment_protection_rule
• deployment_review
• merge_group
• personal_access_token_request
• repository_dispatch

And in some way also ping