Decouple internal/domain/ from internal/request/ package

The internal/request/ package has caused some trouble with circular dependencies, for example !603 (comment 707615505). I also encountered some issues before, but opted for copying code instead for simplicity.

In the example above, I believe the top problem is the internal/request/ package imports the domain package, which ends up importing itself again. From the output

package gitlab.com/gitlab-org/gitlab-pages/internal/domain (test)
	imports gitlab.com/gitlab-org/gitlab-pages/internal/serving/disk/local
	imports gitlab.com/gitlab-org/gitlab-pages/internal/serving/disk
	imports gitlab.com/gitlab-org/gitlab-pages/internal/redirects
	imports gitlab.com/gitlab-org/gitlab-pages/internal/acme
	imports gitlab.com/gitlab-org/gitlab-pages/internal/logging
	imports gitlab.com/gitlab-org/gitlab-pages/internal/request

The output above means domain -> local -> disk -> redirects -> acme -> logging -> request -> domain

So I think ideally we should decouple domain and request first, I'd suggest moving the domain related stuff to the internal/domain/ package

Also break dependency with the internal/acme/ package.

Related to !603 (comment 707615505)