Add redirects of old blog post links and archived versions

[frouioui]

This PR redirects the v19 announcement blog post from the old URL to the new blog post's URL.

It also redirects all old archived docs to their new archived directory.

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[frouioui]

You can test the redirect by going to:

• https://deploy-preview-1771--vitess.netlify.app/docs/16.0/
• https://deploy-preview-1771--vitess.netlify.app/blog/2024-02-28-announcing-vitess-19/