feature/GitHub Enterprise with repo-registration, Argo Workflows, and ArgoCD sync

[bwalsh]

Summary

Integrate support for GitHub App in a GitHub Enterprise environment. This issue tracks the following enhancements for seamless integration and automation:

Acceptance Criteria

• Post-Install Repo-Registration Routing:
  • Implement routing logic that directs users to a repository registration step immediately after installing the GitHub App.
  • Ensure secure handoff and validation during post-install registration.
• Argo Workflows "Run on Push":
  • Enable and configure Argo Workflows to be triggered automatically on push events from registered repositories.
  • Document any configuration requirements for users to enable this automation.
• ArgoCD Application Sync:
  • Integrate ArgoCD so that application syncs can be triggered based on relevant repository events (such as merges to main or new tags).
  • Ensure documentation/support for mapping GitHub events to ArgoCD sync processes.

Additional Context

• The solution should be compatible with both GitHub.com and GitHub Enterprise.
• User and permission handling must meet enterprise security requirements.
• Consider documenting example snippets for workflows and application registration, if possible.