Convert .ci build/test pipelines from Azure DevOps to GitHub Actions - #2018

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@0ad4b8fadaa221de15dcec353f45205ec38ea70b, actions/setup-dotnet@v4, github/codeql-action/analyze@d39d31e687223d841ef683f52467bd88e9b21c14, github/codeql-action/init@d39d31e687223d841ef683f52467bd88e9b21c14. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/