[Feature] GitHub App Authentication

[ryanspletzer]

Is your feature request related to a problem? Please describe.
Our organization is leveraging this via a GitHub Action and wishes to add GitHub App Authentication as alternative to personal access tokens which have to be tied to some type of named user.

Describe the solution you'd like
We would like to have the GitHub action support GitHub App Authentication as an option.

Describe alternatives you've considered
None, the alternatives of a personal access token are already coded into the project.

Additional context
I have already taken a pass at creating this feature on my branch here (first pass, intend to iterate on it if needed), with the intention of opening a PR: ryanspletzer@6cd01be