Replace numpy with MLX as primary array backend in cbook.py

[sydneyrenee]

Summary

• Translates lib/matplotlib/cbook.py from numpy to MLX as the primary array backend
• 207 insertions, 133 deletions across the file
• Maintains API compatibility while leveraging MLX array operations

Test plan

• Run existing cbook tests to verify API compatibility
• Verify MLX array operations produce equivalent results to numpy
• Check edge cases for array type conversions