feat: Add support for GitHub Environments

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Prerequisites:

• Is the functionality available in the GitHub UI? If so, please provide a link to information about the feature.

  • Yes, available under Repository Settings -> Environment
  • https://docs.github.com/en/actions/deployment/targeting-different-environments/using-environments-for-deployment

• Is the functionality available through the GitHub API? If the functionality is available, please provide links to the API documentation (https://developer.github.com/v3/) as well as the Octokit documentation (https://octokit.github.io/).

  • https://docs.github.com/en/rest/deployments/environments

New Feature

Same as repository-settings/app#607
Manage GitHub Environments with safe-settings at settings.yml and {repo}.yml
From #381: Similar to branch protection rules it would be great to configure deployment protection rules, deployment branches, secrets, and variables