Move entity type and ID from base path and into routing parameters

✨ Allow working with a new (unsaved) entity Active is laying the groundwork for this.

This will unblock ✨ [PP-1] Navigate to page/component that's causing a publish error within the same tab Active

✨ Allow working with a new (unsaved) entity Active is pretty much ready: #3529836-11: Enable starting with an empty XB UI (so without first having to create an entity with a component tree) → .

Also would be great to have this by the content templates work so the url for editing a content template can be independent of the entity type and entity in the route