Add lefthook

What does this MR do?

As previously discussed, a lefthook plugin should be implemented to ensure the ref field in .gitlab-ci.yml matches the version (commit hash) of the benchmark submodule. This MR delivers the implementation.

What are the relevant issue numbers?

SAST IDE Integration: add pre-commit hook to en... (gitlab-org/gitlab#473421 - closed) • Hua Yan • 17.3

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Ensure the report version matches the equivalent schema version
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer