chore: make linter to check for unused exported functions

[fmenezes]

Proposed changes

Jira ticket: CLOUDP-#

Closes #[issue number]

Checklist

• [ ] I have signed the MongoDB CLA
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have added any necessary documentation in document requirements section listed in CONTRIBUTING.md (if appropriate)
• [ ] I have addressed the @mongodb/docs-cloud-team comments (if appropriate)
• [ ] I have updated test/README.md (if an e2e test has been added)
• [ ] I have run make fmt and formatted my code

Further comments