feat: add support for required lang param

[Epoxide]

Currently only [[lang]] as an optional param is permitted. This PR makes it possible to use [lang] as a required param as well.

Example:

Routes:

/[lang]
/[lang]/about

Config:

return await sitemap.response({
  origin: 'https://www.example.com',
  page: params.page,
  lang: {
    default: 'en',
    alternates: ['sv', 'nb', 'da'],
  },
})

Output:

<url>
<loc>https://www.example.com/en</loc>
<xhtml:link rel="alternate" hreflang="en" href="https://www.example.com/en"/>
<xhtml:link rel="alternate" hreflang="sv" href="https://www.example.com/sv"/>
<xhtml:link rel="alternate" hreflang="nb" href="https://www.example.com/nb"/>
<xhtml:link rel="alternate" hreflang="da" href="https://www.example.com/da"/>
</url>
<url>
<loc>https://www.example.com/sv</loc>
<xhtml:link rel="alternate" hreflang="en" href="https://www.example.com/en"/>
<xhtml:link rel="alternate" hreflang="sv" href="https://www.example.com/sv"/>
<xhtml:link rel="alternate" hreflang="nb" href="https://www.example.com/nb"/>
<xhtml:link rel="alternate" hreflang="da" href="https://www.example.com/da"/>
</url>
<url>
<loc>https://www.example.com/nb</loc>
<xhtml:link rel="alternate" hreflang="en" href="https://www.example.com/en"/>
<xhtml:link rel="alternate" hreflang="sv" href="https://www.example.com/sv"/>
<xhtml:link rel="alternate" hreflang="nb" href="https://www.example.com/nb"/>
<xhtml:link rel="alternate" hreflang="da" href="https://www.example.com/da"/>
</url>
<url>
<loc>https://www.example.com/da</loc>
<xhtml:link rel="alternate" hreflang="en" href="https://www.example.com/en"/>
<xhtml:link rel="alternate" hreflang="sv" href="https://www.example.com/sv"/>
<xhtml:link rel="alternate" hreflang="nb" href="https://www.example.com/nb"/>
<xhtml:link rel="alternate" hreflang="da" href="https://www.example.com/da"/>
</url>
<url>
<loc>https://www.example.com/en/about</loc>
<xhtml:link rel="alternate" hreflang="en" href="https://www.example.com/en/about"/>
<xhtml:link rel="alternate" hreflang="sv" href="https://www.example.com/sv/about"/>
<xhtml:link rel="alternate" hreflang="nb" href="https://www.example.com/nb/about"/>
<xhtml:link rel="alternate" hreflang="da" href="https://www.example.com/da/about"/>
</url>
<url>
<loc>https://www.example.com/sv/about</loc>
<xhtml:link rel="alternate" hreflang="en" href="https://www.example.com/en/about"/>
<xhtml:link rel="alternate" hreflang="sv" href="https://www.example.com/sv/about"/>
<xhtml:link rel="alternate" hreflang="nb" href="https://www.example.com/nb/about"/>
<xhtml:link rel="alternate" hreflang="da" href="https://www.example.com/da/about"/>
</url>
<url>
<loc>https://www.example.com/nb/about</loc>
<xhtml:link rel="alternate" hreflang="en" href="https://www.example.com/en/about"/>
<xhtml:link rel="alternate" hreflang="sv" href="https://www.example.com/sv/about"/>
<xhtml:link rel="alternate" hreflang="nb" href="https://www.example.com/nb/about"/>
<xhtml:link rel="alternate" hreflang="da" href="https://www.example.com/da/about"/>
</url>
<url>
<loc>https://www.example.com/da/about</loc>
<xhtml:link rel="alternate" hreflang="en" href="https://www.example.com/en/about"/>
<xhtml:link rel="alternate" hreflang="sv" href="https://www.example.com/sv/about"/>
<xhtml:link rel="alternate" hreflang="nb" href="https://www.example.com/nb/about"/>
<xhtml:link rel="alternate" hreflang="da" href="https://www.example.com/da/about"/>
</url>

[jasongitmail]

Awesome. Thanks!

The related test cases should be updated too before merging. If you'd be up to push commits for that, that'd be great (and faster to merge) or I can take a look at it too.

[Epoxide]

Awesome. Thanks!

The related test cases should be updated too before merging. If you'd be up to push commits for that, that'd be great (and faster to merge) or I can take a look at it too.

I can take a look first 👍

[Epoxide]

Actually I'm not quite sure how to do the routes with both [[lang]] and [lang] at the root level without a conflict. Any ideas?

Also I skipped editing the docs in the README as I'm not sure about any other i18n library as I'm not running any third party lib. If you could take a look at that too would be great.

[jasongitmail]

Appreciate you opening this. Closing now that we're focusing on the PR that supports param matchers too. Feel free to jump in on that thread to collaborate on the review. Thanks!