align structure more with underlying chunk layout

src/models/data/data-tracker-status-chunk.ts

@@ -0,0 +1,10 @@
+import { Chunk } from '../chunk';
+
+export interface DataTrackerStatusChunkData {
+  validity: number;
+}
+
+export interface DataTrackerStatusChunk {
+  chunk: Chunk;
+  data: DataTrackerStatusChunkData;
+}