fix: detect Tailwind in PostCSS plugins object

[markdalgleish]

This fixes a Tailwind performance issue when postcss.config.js contains plugins: { tailwindcss: {} } and remix.config.js contains both tailwind: true and postcss: true. This would cause the Tailwind plugin to be applied twice, with the second run of the plugin effectively being an expensive no-op since all Tailwind syntax has already been processed.

Note that this was not an issue when the plugin function had been explicitly called, i.e. plugins: [tailwindcss()]. Remix avoids adding the Tailwind plugin to PostCSS if it's already present but we were failing to detect when the plugin function hadn't been called — either because the plugin function itself had been passed, i.e. plugins: [require('tailwindcss')], or the plugin config object syntax had been used, i.e. plugins: { tailwindcss: {} }.

[changeset-bot]

🦋 Changeset detected

Latest commit: e36328b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 18 packages

Name	Type
@remix-run/dev	Patch
create-remix	Patch
@remix-run/css-bundle	Patch
remix	Patch
@remix-run/architect	Patch
@remix-run/cloudflare	Patch
@remix-run/cloudflare-pages	Patch
@remix-run/cloudflare-workers	Patch
@remix-run/deno	Patch
@remix-run/eslint-config	Patch
@remix-run/express	Patch
@remix-run/netlify	Patch
@remix-run/node	Patch
@remix-run/react	Patch
@remix-run/serve	Patch
@remix-run/server-runtime	Patch
@remix-run/testing	Patch
@remix-run/vercel	Patch

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[github-actions]

🤖 Hello there,

We just published version v0.0.0-nightly-c90c16e-20230524 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!