Explore feasibility of using GitHub App tokens

Potential benefits:
- enables easier methods for instances to gather tokens from users (potentially) by having them authorize a github app (and later revoke if needed)
- higher rate limits (potentially, especially for enterprise installs), at least for installation tokens

https://docs.github.com/en/rest/using-the-rest-api/rate-limits-for-the-rest-api?apiVersion=2026-03-10#primary-rate-limit-for-github-app-installations

https://github.com/red-hat-data-services/rhai-org-pulse/commit/0fd20c81ddf2762a1914aecd8fdb0fa5bcfe37be

https://github.com/red-hat-data-services/rhai-org-pulse/blob/81d03c5f3f4c26888c150da90a0786e2a305d7db/deploy/SECRETS.md?plain=1#L18-L35