[test] Restore t command

[LukasTy]

Fixes #12935

Related to mui/material-ui#40430

Core repo PR description:

This change restores the pre-pnpm behavior of the t script.
With yarn, it was possible to run the test CLI by executing yarn t <test-pattern>. However, pnpm treats t as an alias for test. I introduced a small script that's run whenever pnpm t or pnpm test is executed. It checks if it has any arguments and calls either the test CLI (previous yarn t) or the extended validation suite (previously yarn test)

[mui-bot]

Deploy preview: https://deploy-preview-12948--material-ui-x.netlify.app/

Generated by 🚫 dangerJS against 61e1a8f

[JCQuintas]

Shouldn't we just use pnpm run test --? 😅 seems a script for this is a bit overkill.

Or pnpm run t -- depending on your use-case

[LukasTy]

Shouldn't we just use pnpm run test --? 😅 seems a script for this is a bit overkill.

You can use whatever you are most comfortable with.
This is mainly to be in line with the Contributing guidelines, which are directly "inherited" from the mui/material-ui.
Personally, I almost exclusively use test:unit --grep <whateverIWantToTest>. 🤷