fix/improve behavior of "sorted" attribute

src/services/note_cache/entities/note.js

@@ -133,6 +133,14 @@ class Note {
         return !!this.attributes.find(attr => attr.type === type && attr.name === name);
     }
 
+    hasLabel(name) {
+        return this.hasAttribute('label', name);
+    }
+
+    hasRelation(name) {
+        return this.hasAttribute('relation', name);
+    }
+
     getLabelValue(name) {
         const label = this.attributes.find(attr => attr.type === 'label' && attr.name === name);
 
@@ -275,6 +283,11 @@ class Note {
         return arr.flat();
     }
 
+    /** @return {String[]} */
+    get subtreeNoteIds() {
+        return this.subtreeNotes.map(note => note.noteId);
+    }
+
     get parentCount() {
         return this.parents.length;
     }