Add msgraph-sdk skill for Microsoft Graph SDK integration (.NET, TypeScript, Python)

[lovyjain]

Pull Request Checklist

• I have read and followed the CONTRIBUTING.md guidelines.
• I have read and followed the Guidance for submissions involving paid services.
• My contribution adds a new skill file in the correct directory.
• The file follows the required naming convention.
• The content is clearly structured and follows the example format.
• I have tested my skill with GitHub Copilot.
• I have run npm start and verified that README.md is up to date.
• I am targeting the staged main` for this pull request.

---

Description

Adds a new msgraph-sdk skill covering Microsoft Graph SDK integration for .NET, TypeScript, and Python. covers auth patterns (client credentials, OBO, managed identity, device code), core SDK usage, batching, delta queries, webhooks, throttling, and least-privilege permissions. Includes language-specific reference files for all three ecosystems.

---

Type of Contribution

• [ msgraph-sdk] New skill file.

---

Additional Notes

---

By submitting this pull request, I confirm that my contribution abides by the Code of Conduct and will be licensed under the MIT License.

[github-actions]

⚠️ This PR targets main, but PRs should target staged.

The main branch is auto-published from staged and should not receive direct PRs.
Please close this PR and re-open it against the staged branch.

You can change the base branch using the Edit button at the top of this PR,
or run: gh pr edit 1683 --base staged