Add --ci flag to the types command to allow checking for out of date types with ci/scripts

[pjrobertson]

Fixes #261

Checklist

• only relevant code is changed (make a diff before you submit the PR)
• run tests npm run test NOTE: 2 tests still failing from previously
• tests are included
• commit message and code follows the Developer's Certification of Origin

[adrai]

Merged and released in v1.59.0 🚀

Thanks again for the clean implementation and tests, @pjrobertson! I also added docs for types --ci (command options + a CI/CD snippet) in a follow-up commit. You can now drop the git diff scripting in favor of:

- name: Check i18n Resources Schema
  run: npx i18next-cli types --ci

FYI the 2 test failures you noted in the checklist didn't reproduce here — the full suite (1059 tests) passes locally and the flag was verified end-to-end. If you still see those 2 failing on your machine, let me know which ones and I'll take a look.

[pjrobertson]

I've created a separate bug report, it may be a false positive because my setup is not quite right - feel free to close if it's irrelevant