Create Github App to allow CI/CD workflow to push to protected branches

In order to run the same CI/CD on the Xilinx, ADSP and O-RAN branches we need to keep `.github` and `ci/` in sync on each branch. A workflow therefore needs to synchronize them by committing on the branches.

https://github.com/orgs/community/discussions/25305#discussioncomment-8256560