Move the Markdown component to its own package

[matthewp]

Changes

• This moves the <Markdown> component to its own package.
• Package is called @astrojs/markdown. Can still change if another name is preferred.
• Depends on Remove Markdown special-casing compiler#472

Testing

• Moved over as many of the tests as I could.

Docs

• Remove references to the <Markdown> component docs#1045

[changeset-bot]

🦋 Changeset detected

Latest commit: ce1b36c

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

This PR includes changesets to release 10 packages

Name	Type
astro	Minor
@astrojs/markdown-component	Minor
@e2e/astro-component	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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[natemoo-re]

RIP! Looks good but had a few questions.

[delucis]

Not a showstopper, but do we think that @astrojs/markdown is too juicy a package name? Might attract folks when we really want to put them off using this? Maybe even something as explicit as @astrojs/markdown-component or @astrojs/static-markdown-component to make it seem less enticing.

[tony-sull]

lgtm!