APP-7824: Added support for AtlanClient creation via api token guid

[Aryamanz29]

✨ Description

https://atlanhq.atlassian.net/browse/APP-7824

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🧩 Type of change

Select all that apply:

• 🚀 New feature (non-breaking change that adds functionality)
• 🐛 Bug fix (non-breaking change that fixes an issue) — please include tests! Refer testing-toolkit 🧪
• 🔄 Refactor (code change that neither fixes a bug nor adds a feature)
• 🧹 Maintenance (chores, cleanup, minor improvements)
• 💥 Breaking change (fix or feature that may break existing functionality)
• 📦 Dependency upgrade/downgrade
• 📚 Documentation updates

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✅ How has this been tested? (e.g. screenshots, logs, workflow links)

https://lt008.atlan.com/workflows/profile/csa-metadata-completeness-1753439230/runs?name=csa-metadata-completeness-1753439230-94q7t

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📋 Checklist

• My code follows the project’s style guidelines
• I’ve performed a self-review of my code
• I’ve added comments in tricky or complex areas
• I’ve updated the documentation as needed
• There are no new warnings from my changes
• I’ve added tests to cover my changes
• All new and existing tests pass locally