Allow automatic JSX runtime alongside MDX

[matthewp]

Changes

• Instead of using the automatic runtime to append Astro JSX, this makes it so that we use the pragma comment /** @jsxImportSource astro */ to make our Astro JSX (MDX) files get the right jsx runtime import.
• This means that you can rely on the automatic imports for other renderers, like React.
• Fixes 🐛 BUG: React + MDX: React is not defined #4084

Testing

• Test added
• Other tests still passing

Docs

N/A, bug fix

[changeset-bot]

🦋 Changeset detected

Latest commit: 258aac0

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

This PR includes changesets to release 13 packages

Name	Type
astro	Patch
@astrojs/mdx	Patch
@e2e/astro-component	Patch
@e2e/error-react-spectrum	Patch
@e2e/error-sass	Patch
@e2e/errors	Patch
@e2e/lit-component	Patch
@e2e/preact-component	Patch
@e2e/react-component	Patch
@e2e/solid-component	Patch
@e2e/svelte-component	Patch
@e2e/e2e-tailwindcss	Patch
@e2e/ts-resolution	Patch

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[matthewp]

Closing for now as #4137 might fix this a better way.