Send host header to Decoupled Router.

[longwave]

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• examples/*
• modules/next
• packages/next-drupal
• starters/basic-starter
• starters/graphql-starter
• starters/pages-starter
• Other

GitHub Issue: #332
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Describe your changes

This is an alternative to the suggestion in #332, instead of needing different Drupal base URLs we pass on the host header from the original request as a query parameter to Decoupled Router. I also have an extended version of Decoupled Router that interprets that query parameter and passes it to Domain module, allowing decoupled multi-domain setups with a single Drupal backend URL.

[vercel]

@longwave is attempting to deploy a commit to the Chapter Three Team on Vercel.

A member of the Team first needs to authorize it.

[longwave]

Well, except this doesn't really work because it makes all requests dynamic as soon as you look at headers; it works in development mode but not in a production build.