chore: replace jest with mocha VSCODE-516

[mcasimir]

Description

Checklist

• [ ] New tests and/or benchmarks are included
• [ ] Documentation is changed or added
• [ ] I have signed the MongoDB Contributor License Agreement (https://www.mongodb.com/legal/contributor-agreement)

Motivation and Context

• [ ] Bugfix
• [ ] New feature
• [ ] Dependency update
• [ ] Misc

Open Questions

Dependents

Types of changes

• [ ] Backport Needed
• [ ] Patch (non-breaking change which fixes an issue)
• [ ] Minor (non-breaking change which adds functionality)
• [ ] Major (fix or feature that would cause existing functionality to change)