Support organization-scope installation token

[kmaehashi]

Thank you for making a great Action! We've been relying on third-party actions or raw github-script for a long time, so it's great to see the official solution finally!

One request I'd like to make is to support retrieving organization-scoped installation token. One of the example use-cases is to automate the GitHub Project (V2), as illustrated in the GitHub's official documentation (which currently uses tibdex/github-app-token):

https://docs.github.com/en/issues/planning-and-tracking-with-projects/automating-your-project/automating-projects-using-actions

GitHub Project (V2) is a resource tied to organizations, so repository-scope access should be essentially unnecessary for the App.

[gr2m]

can we close this issue in favor of #4?

[kmaehashi]

Thanks, sounds good to close!