feat(clusterkubeconfigs): add labels from cluster resource

[onuryilmaz]

Description

This PR adds a functionality to mirror labels of the cluster resource to clusterkubeconfig resource. These labels will be used by client tools to classify clusters.

What type of PR is this? (check all applicable)

• 🍕 Feature
• 🐛 Bug Fix
• 📝 Documentation Update
• 🎨 Style
• 🧑‍💻 Code Refactor
• 🔥 Performance Improvements
• ✅ Test
• 🤖 Build
• 🔁 CI
• 📦 Chore (Release)
• ⏩ Revert

Related Tickets & Documents

cloudoperators/cloudctl#27

Added tests?

• 👍 yes
• 🙅 no, because they aren't needed
• 🙋 no, because I need help
• Separate ticket for tests # (issue/pr)

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

Added to documentation?

• 📜 README.md
• 🤝 Documentation pages updated
• 🙅 no documentation needed
• (if applicable) generated OpenAPI docs for CRD changes

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes