MAINT: Extract technique factory resolution from MatrixAtomicAttackBuilder (#2869)

[Vardhman Gupta (Kaap10)]

Description

Fixes #2869

While exploring technique resolution across different scenario architectures, I noticed that pyrit/scenario/core/matrix_atomic_attack_builder.py combined both matrix combinatorial expansion and generic technique factory resolution/validation logic (resolve_technique_factories, resolve_technique_factories_for_techniques, and TechniqueResolutionError).

As highlighted in the builder's module docstring, scenarios of different shapes (such as adaptive scenarios, composite builders, or per-objective builders) also need technique resolution from AttackTechniqueRegistry and extra_factories, but they shouldn't need to import or couple with matrix_atomic_attack_builder.py.

This PR extracts the technique resolution and missing technique validation logic into a dedicated private helper module:

1. Created pyrit/scenario/core/_technique_resolution.py containing TechniqueResolutionError, resolve_technique_factories, and resolve_technique_factories_for_techniques with complete Google/Sphinx style docstrings.
2. Re-exported all resolution symbols in pyrit/scenario/core/matrix_atomic_attack_builder.py (with explicit __all__) and registered lazy exports in pyrit/scenario/core/__init__.py to ensure complete backward compatibility for external callers and legacy imports.
3. Updated internal consumers in pyrit/scenario/core/scenario.py to import directly from _technique_resolution.

Tests and Documentation

• Moved dedicated unit tests to tests/unit/scenario/core/test_technique_resolution.py covering context resolution, sequence resolution, error deduplication in first seen order, ValueError inheritance, and extra_factories overrides.
• Added backward-compatibility re-export identity assertions in tests/unit/scenario/core/test_matrix_atomic_attack_builder.py.
• Updated mock patch targets in tests/unit/scenario/test_default_run_size_estimates.py to point to _technique_resolution.
• Ran the full scenario unit test suite (pytest tests/unit/scenario/), all 1,268 unit tests passed.
• Verified linting and formatting with ruff check and ruff format, all checks passed with 0 errors.

[Vardhman Gupta (Kaap10)]

Hi Roman Lutz (@romanlutz), this PR extracts technique factory resolution into a dedicated module per #2869 with full test parity. Whenever you have some time, could you please take a look and approve the workflow run? Thanks!

[Vardhman Gupta (Kaap10)]

Hi Roman Lutz (@romanlutz),

Thanks for the review! I have addressed both points in the latest commit (b0417efa):

1. Private Helper Module: Renamed technique_resolution.py to pyrit/scenario/core/_technique_resolution.py to keep the implementation private while maintaining all public re-exports from pyrit.scenario.core and matrix_atomic_attack_builder.
2. Deduplicated Resolver Tests & Compatibility Checks: Moved the resolver test suite into test_technique_resolution.py and replaced the duplicates in test_matrix_atomic_attack_builder.py with TestLegacyReExports to verify identity (is) for all legacy re-exports.

All linting checks (ruff) and unit tests (pytest tests/unit/scenario/ - 1,268 tests) pass cleanly. Please let me know if anything else is needed!