🧪 Add tests for serve.py component_platforms

[Ch3fUlrich]

• 🎯 What: Added missing tests for the component_platforms function in lib/linux/serve.py.
• 📊 Coverage: The new test covers reading from multiple dummy platform catalog JSON files, checking that it correctly maps component IDs to the list of platforms that contain them.
• ✨ Result: Increased test coverage and confidence in the platform dependency resolution logic.

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PR created automatically by Jules for task 10259318511769049438 started by @Ch3fUlrich

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