[FEAT]: List installed GitHub Apps in an organization

[AureliaAutem]

Describe the need

It would be nice to be able to list installed GitHub Apps within an organization, in particular to integrate with existing resources such as github_app_installation_repository.
The API is already available: https://docs.github.com/en/rest/orgs/orgs?apiVersion=2022-11-28#list-app-installations-for-an-organization

We would be able to do something like this:

# Feat: List all installed apps in the organization
data "github_app_installations" "all_apps" {}

# Feat: Fetch a specific github app
data "github_app_installation" "my_app" {
  slug = "myapp"
}

# Example of integration
resource "github_app_installation_repository" "some_app_repo" {
  # The installation id of the app (in the organization).
  installation_id    = data.github_app_installation.my_app.id
  repository         = "${github_repository.some_repo.name}"
}

SDK Version

No response

API Version

No response

Relevant log output

Code of Conduct

• I agree to follow this project's Code of Conduct

[atilsensalduz]

Hey! I've just opened a PR to add the github_organization_app_installations data source.
This is my first contribution to the GitHub Terraform provider, so I hope I got everything right!

I ran the acceptance tests, and everything looked good on my end.
I'd love to hear your thoughts. Please let me know if I missed anything or if you'd like me to make any changes.

Thanks!