Allow sites to have multiple base URLs

[timkelty]

Sites inherently have different URLs in different environments, which means a sites's Base URL almost always needs to be environment variable (PRIMARY_SITE_URL is suggested by Craft's installer).

When multiple sites are involved, that ends up being a lot of arbitrarily named environment variables to manage.

Allowing multiple base URLs to match against when determining the site simplifies this, while also allowing situations where you may want multiple valid site base URLs for the same, or different, environments:

• Primary site: https://mysite.com, https://mysite-production-1234abc.preview.craft.cloud, https://mysite-staging-1234abc.preview.craft.cloud, https://mysite.ddev.site
• FR site: https://mysite.fr, https://mysite-production-1234abc.preview.craft.cloud/fr, https://mysite-staging-1234abc.preview.craft.cloud/fr, https://mysite.ddev.site/fr

[brandonkelly]

Decided not to do this after discussing internally.

If a request came in for x.preview.craft.cloud, that could inform that the current site should use x.preview.craft.cloud as its selected base URL, but there’s no way Craft would be able to infer from that, that other sites should use x.preview.craft.cloud/nl (or whatever) as their selected base URLs as well. So it’s not a perfect solution.

Instead, the Cloud extension (e.g.) should start detecting requests where the host ends in preview.craft.cloud, and override each site’s base URLs on its own.

• Primary site: x.preview.craft.cloud
• Secondary sites: x.preview.craft.cloud/site/<handle>