Sync: Index imported post

I worked on a ticket today where an user setup a new site and imported old content. No full sync was performed on the site and imported posts were not synced up to the site.

This issue is for us to verify we're picking up imported posts.

Start by reproducing the reported setup: create a new site, import old content, and omit a full sync. Trace how imported posts are handled during sync and verify whether they are picked up; done means imported posts are synced correctly without requiring a separate full sync.

Written by the indexing model from the issue text.