Mark tailwindcss as an optional dependency of CRA

Created by: ioanabrooks

Is your proposal related to a problem?

react-scripts should havetailwindcss as an optional dependency to prevent issues with tailwind, such as this recent issue to break CRA builds.

Describe the solution you'd like

There has been an attempt made in this PR: https://github.com/facebook/create-react-app/pull/12046

Describe alternatives you've considered

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Additional context

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