feat: Backlinks (#979)

* feat: backlinks

* feat: add backlinkDocumentId to documents.list

* chore: refactor
fix: create and delete backlink handling

* fix: guard against self links

* feat: basic frontend
fix: race condition

* styling

* test: fix parse ids

* self review

* linting

* feat: Improved link styling

* fix: Increase clickable area at bottom of doc / between references

* perf: global styles are SLOW

server/pages/developers/Api.js

@@ -219,6 +219,11 @@ export default function Api() {
                 id="collection"
                 description="Collection ID to filter by"
               />
+              <Argument id="user" description="User ID to filter by" />
+              <Argument
+                id="backlinkDocumentId"
+                description="Backlinked document ID to filter by"
+              />
             </Arguments>
           </Method>