Enhance NativePythonFinderImpl with improved logging and configuration comparison

[karthiknadig]

Summary

This PR implements code quality improvements for ativePythonFinder.ts as identified in #1142.

Changes

1. Type Guard for isNativeEnvInfo()

Changed return type from boolean to info is NativeEnvInfo for proper TypeScript type narrowing.

2. Robust Configuration Comparison

Replaced fragile JSON.stringify() comparison with a dedicated configurationEquals() method that:

• Compares properties individually
• Uses sorted array comparison to handle order differences
• Avoids issues with undefined value serialization

3. Cache Key Collision Prevention

Changed the separator for cache keys from , to \0 (null character) to prevent collisions with paths containing commas.

4. Standardized Logging

Converted traceVerbose calls within NativePythonFinderImpl to use outputChannel.debug() for consistent instance-level logging. Removed unused import.

5. Graceful Shutdown

Added a graceful shutdown mechanism that closes stdin before killing the process, giving it 500ms to clean up.

6. Documentation

Added explanatory comment for the intentional duplicate venvFolders fetch explaining why it's needed when searchPaths may override environmentDirectories.

Fixes #1142

[eleanorjboyd]

@copilot add testing for functionality introduced here and also to confirm the Cache Key Collision Prevention and Type Guard for isNativeEnvInfo() is working.

[Copilot]

@eleanorjboyd I've opened a new pull request, #1151, to work on those changes. Once the pull request is ready, I'll request review from you.