Optimize page load observers #39
Description
Specifically the linkedReferencesObserver, as it contains a roam query.
We should look into combining/optimizing this with the pageTitleObserver and upcoming features nanopub/GitHub publishing.
Many of these require checking if the page is a discourse node, which often can require a query. If this is the case, we should only do this once and make the result available to the other functions/features.