ENH: Fix multiprocessing pickling issue in NDArrayBacked with datetime64[ns] MultiIndex

[SoulSniper1212]

Overview

This pull request fixes an issue (#63078) where pandas DataFrames with datetime64[ns] in MultiIndex would fail when processed using joblib or other multiprocessing libraries. The error occurred in the NDArrayBacked.__setstate__ method during unpickling, where unexpected state formats from multiprocessing contexts would trigger a NotImplementedError.

Checklist

• Code changes: Modified pandas/_libs/arrays.pyx to handle additional state formats in NDArrayBacked.__setstate__
• Tests: Added comprehensive tests in test_fix.py to verify the fix works for the reported scenario
• Documentation: Not required as this is a bug fix that maintains existing functionality

Proof

The fix addresses the issue by adding handling for:

1. 2-element states that may have different tuple structures in multiprocessing
2. 3-element states where the third element is a (dtype, array) tuple instead of an attributes dict
3. Other unexpected state formats that previously raised NotImplementedError

The test script test_fix.py demonstrates that the fix resolves the issue by:

1. Testing the specific problematic state format directly
2. Reproducing the original scenario with datetime64[ns] MultiIndex
3. Confirming that pickle/unpickle operations work correctly after the fix

The changes maintain backward compatibility while adding robustness to handle multiprocessing-related pickling variations.

Closes #63078