[WIP] Port #60195

[Copilot]

Port microsoft/TypeScript PR #60195: Include non-enumerable keys in __importStar helper

This change updates the __importStar emit helper to include non-enumerable properties when performing star imports, matching the behavior implemented in TypeScript commit 2e4f2c7.

Plan:

• Analyze the changes needed from the original TypeScript commit
• Locate the corresponding emit helper code in the Go port (internal/printer/helpers.go)
• Verify current build and test status
• Update the importStarHelper text to use Object.getOwnPropertyNames approach
• Build the project to ensure it compiles
• Run tests and expect baseline changes
• Accept baseline changes if they align with expected behavior
• Verify the change produces correct emit output

The key change involves replacing the simple for...in loop with a more sophisticated approach that:

1. Uses Object.getOwnPropertyNames when available to include non-enumerable properties
2. Falls back to the original for...in approach for compatibility
3. Wraps the logic in an IIFE for proper scoping

Fixes #7.

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