Make wco-docs-page component and move nav HTML generation into it

[aomarks]

• Make a wco-docs-page component
• Move nav HTML generation into wco-nav-page component
• Fix hydration of docs page

Also:

• Rename hydrate.js to hydrate-support.js
• Move hydrate-support directly into base template

[github-actions[bot]]

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https://pr1412---site-khswqo4xea-wl.a.run.app/

Warning Until our Cloud Run project is public, only authorized users can view the above URL. The easiest way to view it authenticated is to run the following proxy command and visit http://localhost:5453

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