MOBILE-3371 core: Improve manager sources

src/core/classes/items-management/items-manager-source.ts

@@ -36,6 +36,15 @@ export abstract class CoreItemsManagerSource<Item = unknown> {
         this.loadedPromise = new Promise(resolve => this.resolveLoaded = resolve);
     }
 
+    /**
+     * Check whether the source is dirty.
+     *
+     * @returns Whether the source is dirty.
+     */
+    isDirty(): boolean {
+        return this.dirty;
+    }
+
     /**
      * Check whether data is loaded.
      *