Extend to Github Enterprise Server

[coolhome]

Is your feature request related to a problem? Please describe.

To support Github Enterprise Server

Describe the solution you'd like

Octokit.GithubClient supports both Github and Github Enterprise Server. In theory we should be able to expand with a few more parameters.

https://github.com/octokit/octokit.net/blob/main/docs/getting-started.md#connect-to-github-enterprise

[BernieWhite]

@coolhome Nice thought.