feature: support self hosted vcs

[jaredfholgate]

Overview/Summary

Adding the ability to override SaaS hosted GitHub and Azure DevOps with a self-hosted VCS url.

NOTE: This is not something we can test and some features, such as Workload identity federation will not work with self hosted yet.

This PR fixes/adds/changes/removes

1. Feature Request: Support self hosted VCS #13

Breaking Changes

None

Testing Evidence

Please provide any testing evidence to show that your Pull Request works/fixes as described and planned (include screenshots, if appropriate).

As part of this Pull Request I have

• Checked for duplicate Pull Requests
• Associated it with relevant issues, for tracking and closure.
• Ensured my code/branch is up-to-date with the latest changes in the main branch
• Performed testing and provided evidence.
• Updated relevant and associated documentation.

[luke-taylor]

Approving with comments - just curious if there exists a combintion of input variables that would break the code i.e. self-hosted VCS trying to use federated credentials etc.