refactor: usage formatting

[BobbieGoede]

This is only a refactor, theres should be no behavioral changes and hopefully this makes it a bit easier to change the argument usage formatting.

I noticed we're only printing the defaults for string and positional arguments, I can imagine this would be useful for number and enum too (not sure about boolean though), I'll open a PR for that if I have time.

[codecov]

Codecov Report

❌ Patch coverage is 95.65217% with 2 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (main@f96cbbb). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
src/usage.ts	95.65%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #208   +/-   ##
=======================================
  Coverage        ?   93.73%           
=======================================
  Files           ?        7           
  Lines           ?      527           
  Branches        ?      168           
=======================================
  Hits            ?      494           
  Misses          ?       33           
  Partials        ?        0           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[BobbieGoede]

Ah, I'm too late again!

This PR has some overlap with #198, that PR includes changes I was going to look into after this one. I'll close this in favor of that one, it looks good to me.