Add stale PR probot

[johnewing1]

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Description

Add bot to project to automatically mark abandoned issues and PRs

Initial settings are: Mark PRs or issues with no activity for more than 360 days as stale Auto close PRs or issues if there is no further activity in the 30 days after being marked as stale

Type of change

Github config change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

How has this been tested?

Repo config change, no code touched

Checklist:

• [x] This contribution follows the project's code of conduct
• [x] This contribution follows the project's contributing guidelines
• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [ ] Any dependent changes have been merged and published in downstream modules