🧪 [Add tests for ScriptMutex::lock]

[Tcode-Motion]

🎯 What: Added a test for the ScriptMutex::lock function in stdlib/src/sync.rs which was previously untested.
📊 Coverage: The test covers locking from multiple threads and ensuring a thread blocks until the lock is available.
✨ Result: Improved test coverage and confidence in the functionality of ScriptMutex::lock and ScriptMutex::unlock.

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PR created automatically by Jules for task 16385156435273164538 started by @Tcode-Motion

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