Add .mjs & .cjs matching to semgrep analyzer

What does this MR do?

enable support for .mjs & .cjs scanning

What are the relevant issue numbers?

Enable Semgrep SAST job to scan *.mjs and *.cjs... (gitlab-org/gitlab#464555) • Tal Kopel • 17.2

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 updated/added for this feature/bug
• Job definition updated, if necessary
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer