Add reactStrictMode as an option to render

[bernardobelchior]

What:

Add an ability to override the global reactStrictMode configuration on a per-test basis.

Why:

At MUI, our tests use a small wrapper around React Testing Library and had this functionality. However, it was broken in the upgrade to React 19 since StrictMode won't double call effects on initial mount unless StrictMode is rendered at the root of the tree. Since we were rendering React.StrictMode inside the component passed to the wrapper property, effects aren't being called twice in React 19.

How:

Added a reactStrictMode to renderOptions.

Checklist:

• Documentation added to the docs site: Update docs with reactStrictMode in render testing-library-docs#1479
• Tests
• TypeScript definitions updated
• Ready to be merged
  

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[eps1lon]

flawless. Thank you! Will merge once docs are settled.

[eps1lon]

@all-contributors add @bernardobelchior for code, docs

[allcontributors]

@eps1lon

I've put up a pull request to add @bernardobelchior! 🎉