Upgrade to Docusaurus v3

[sserrata]

Description

WHAT:

• Upgrading Docusaurus to latest 3.6.3 release for pan.dev
• Upgrading the OpenAPI plugin to latest release with v3 support

WHY:

• Faster builds and better developer/contributing experience!
• Improvements to OpenAPI plugin/theme

CHANGES:

• sidebars.js have been renamed to sidebars.ts

OTHER:

• Important reminder that md and mdx files are now handled differently. Please stick to using md extension unless you need an MDX/JSX specific component.
• PRs currently open will likely have merge conflicts after the upgrade is complete. Since I cannot tell which PRs we are actually planning to merge, please reach out here if you need some help resolving those conflicts.

Preview: https://pan-dev-f1b58--pr667-4fkdzexb.web.app/

TODO:

• Refactor sidebars.js to sidebars.ts modules
• Refactor all sidebar.js to sidebar.ts modules
• Refactor docusaurus config as necessary
• Address all MDX syntax errors (mostly expedition and swfw docs)

[sserrata]

Build is currently failing with an error similar to the one reported here: facebook/docusaurus#9907

[github-actions]

Visit the preview URL for this PR (updated for commit 6d34750):

https://pan-dev-f1b58--pr667-4fkdzexb.web.app

_{(expires Thu, 09 Jan 2025 22:53:59 GMT)}

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_{Sign: 9359a9fa100d5fdb082f75280473a90b1f96eb51}

[sserrata]

@blindaa121 just upgraded to latest docusaurus and openapi plugin canary. Aside from the merge conflicts we'll also want to make sure we pull in all the changes that occurred since the last time I updated this branch.