[Page] Extend meta attributes

As a web producer, I want the pages of my site to be enhanced with Open Graph and SEO metadata, so that linking to my pages in social media makes the preview display relevant information.

As for the OpenGraph tags, typical requirements are to have the following:
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The social media tags typically look like so:
```

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Additionally, there also should be a canonical tag for SEO purposes:
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No files, tests, or entry points are named. Start by locating where page head metadata is produced, then determine how the requested Open Graph, Twitter, social-account, SEO, and canonical values should be supplied; done means the generated pages contain the required tags with relevant values.

Written by the indexing model from the issue text.