Add benchmark

What does this MR do?

add the sast-ide-benchmark repo as a submodule, for benchmarking.

What are the relevant issue numbers?

gitlab-org&13940 (comment 1939557887)
https://gitlab.com/gitlab-org/secure/static-analysis/sast-ide-benchmark/-/issues/1+s

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

Related issues

https://gitlab.com/gitlab-org/secure/static-analysis/sast-ide-benchmark/-/issues/3