GitHub App registration

## Prerequisites:

* Is the functionality available in the GitHub UI? If so, please provide a link to information about the feature.

Yes, once an app is installed in the organization you can configure it and "install" it on specific repositories.

* Is the functionality available through the GitHub API? If the functionality is available, please provide links to the
API documentation (https://developer.github.com/v3/) as well as the Octokit documentation (https://octokit.github.io/).
Yes, https://docs.github.com/en/rest/apps/installations#add-a-repository-to-an-app-installation

* If the functionality is not yet available in the API, it would be helpful if you
contacted support (https://support.github.com/) or posted in the Community Forum (https://github.community/). Please
include a link to the forum post if you create one or a copy of the response from support.

## New Feature

Within an organization, teams usually create GitHub Apps for their CI/CD workflows. These apps need to be transferred to the organization owners. Once this is done, installing the app onto specific repositories can only be done by organization owners.

It would be desired if teams could request the "installation" of the apps by themselves through IaC, in this case safe-settings configurations.

This is for example implemented in the Terraform GitHub Provider: https://registry.terraform.io/providers/integrations/github/latest/docs/resources/app_installation_repository