perspectives: added data provider layer

packages/datalib/src/PerspectiveDataProvider.ts

@@ -0,0 +1,14 @@
+import { PerspectiveDataLoadProps } from './PerspectiveTreeNode';
+
+export interface PerspectiveDataCache {}
+
+export class PerspectiveDataProvider {
+  constructor(
+    public cache: PerspectiveDataCache,
+    public setCache: (value: PerspectiveDataCache) => void,
+    public loader: (props: PerspectiveDataLoadProps) => Promise<any[]>
+  ) {}
+  async loadData(props: PerspectiveDataLoadProps) {
+    return await this.loader(props);
+  }
+}