QubitOperator upgrades

[renezander90]

Description

This PR improves the performance of Hamiltonian term grouping and qubit-wise commutativity checks. It replaces NetworkX graph construction with NumPy adjacency matrices, and reduces the work performed by QubitTerm.commute_qw() for sparse terms.

Related Issues

Closes #
Related to #

Type of Change

• Feature (new functionality)
• Change Request (modification of existing functionality)
• Bug Fix
• Refactoring (no behavior change)
• Performance improvement
• Documentation
• CI / Build

Breaking Change?

• Yes
• No

If yes, describe the impact and migration path:

What was changed?

• Replaced NetworkX-based graph construction in group_up_iterable() with a NumPy adjacency matrix.
• Added type annotations and documentation for the Hamiltonian grouping utilities.
• Preserved the existing coloring behavior while avoiding NetworkX conversion and graph-management overhead.
• Optimized QubitTerm.commute_qw() by iterating over the smaller factor dictionary.
• Kept the existing grouping and commutativity APIs unchanged.

Checklist

• My code follows the project's coding standards
• I have performed a self-review
• I have added/updated tests (referencing issue Test-IDs)
• All tests pass locally and in CI
• I have updated the documentation
• I have added a changelog entry to changelog-dev.rst
• Breaking changes are documented with migration path