Feature: Audit installed GitHub apps

[azeemshaikh38]

Org admins can use AllStar to audit all the GitHub apps they have installed and the permission each app has. This could just be a way for admins to monitor their installations across orgs and repos, but can easily be made into an AllStar policy which lets admins define a allowList/denyList of apps and their permissions.

Relevant GitHub API - https://docs.github.com/en/rest/orgs/orgs#list-app-installations-for-an-organization