Push to separate repo

[ashawley]

• Objective: Push integration branch to a separate repository, rather than the same repository the base branch and PRs are located.
• Presently, pushing integration branch can only be done to the same repository.
• Rationale: This process should not have git access to the base repo. GitHub doesn't support it with private repos, but this follows the principle of least privilege. Further, automated integration work shouldn't interfere with the commit activities of the main repository. This function in AWS Lambda, will ignore push events from itself, but it is orthogonal to the usual git activity of the repo that is bound to have unnecessary consequences.
• Safety: If the separate repo doesn't exist?
• Configuration: Support pushing to same repo and separate repo?