finish onboarding exercises

[Shawnhec]

Checklist

Please ensure you have followed all of the steps below before submitting a pull request:

• Test your code (npm test or npm run test)
• Check your types (npm run typecheck)
• Lint your code (npm run lint)
• Format your code (npm run format)
• Document your code with TSDoc comments

Overview

This PR completes the onboarding exercises.

Key changes:

• Implemented required algorithm in exercise 01.
• Wrote TSDoc description for the function in exercise 02.
• Fixed the TypeScript errors in the file without changing the intended behavior in exercise 03.
• Resolved the linting issues in exercise 04.
• Reformatted file of exercise 05.

Test Plan

I verified all components locally within the terminal before pushing:

1. npm run typecheck - 0 errors found.
2. npm run lint & npm run format - 0 issues found and and files formatted.
3. npm run test - All mock tests of exercise 01 passed.

[CaptainExtremis]

All checks pass, code looks clean. Well done, Shawn!

[dvorakjt]

Approved.