QUAL-017: introduce BuildContext value object for job builders

[ydesgagn]

Summary

Resolves the QUAL-017 data-clump finding from the deep code review. The recurring { options, old_workflow, new_workflow, file_cache, submodules } keyword-argument clump threaded into every job builder is replaced by a single immutable GHB::BuildContext value object. Behaviour-preserving — the existing 321-example suite passes unchanged and RuboCop is clean across all 46 files.

Key changes:

• New lib/ghb/build_context.rb — immutable value object holding options, old_workflow, new_workflow, file_cache, submodules (referenced objects are still mutated in place by the pipeline; only the container is frozen).
• Application#execute builds one BuildContext and passes it to all builders; per-builder extras (unit_tests_conditions, dependencies_commands, code_deploy_pre_steps) remain explicit keyword args alongside context:.
• All 8 builders/managers updated to initialize(context:, ...) and destructure from it: variables, linter, licenses, language, code_deploy, aws, slack job builders + gitignore_manager.
• 8 corresponding builder specs updated to construct via GHB::BuildContext.new(...).

Types of changes

• Bugfix (fixes an issue)
• New feature (adds functionality)
• Refactoring (improves code without changing functionality)
• Breaking change (incompatible changes)
• Build or security update (updates dependencies, libraries, or security patches)
• Code style or documentation update (formatting, renaming, or documentation changes)
• Other (please describe):

Checklist

• Unit tests added to validate my fix/feature
• I have manually tested my change
• I did not add automation test. Why ?: Behaviour-preserving refactor; the existing 321-example suite (updated for the new constructor) covers these paths and passes unchanged.
• Database changes requiring migration with downtime or reprocessing of existing data
• The SOUP file lists the risk Level, requirements and verification reasoning associated with each library
• `readme.md` includes sections on introduction, installation, usage, and contributing
• `docs/architecture.md` includes sections on the architecture diagram, software units, software of unknown provenance, critical algorithms and risk controls related to PII and security
• Impact on PII, privacy regulations (CCPA/GDPR/PIPEDA), CIS benchmarks or security (availability/confidentiality/integrity); management must be notified