Improve remote sketchbook explorer (#459)

* Refactor remote sketchbook explorer
* sketches sorting

arduino-ide-extension/src/browser/widgets/cloud-sketchbook/cloud-sketch-cache.ts

@@ -0,0 +1,34 @@
+import { FileStat } from '@theia/filesystem/lib/common/files';
+import { injectable } from 'inversify';
+import { toPosixPath } from '../../create/create-paths';
+import { Create } from '../../create/typings';
+
+@injectable()
+export class SketchCache {
+  sketches: Record<string, Create.Sketch> = {};
+  fileStats: Record<string, FileStat> = {};
+
+  init(): void {
+    // reset the data
+    this.sketches = {};
+    this.fileStats = {};
+  }
+
+  addItem(item: FileStat): void {
+    this.fileStats[item.resource.path.toString()] = item;
+  }
+
+  getItem(path: string): FileStat | null {
+    return this.fileStats[path] || null;
+  }
+
+  addSketch(sketch: Create.Sketch): void {
+    const { path } = sketch;
+    const posixPath = toPosixPath(path);
+    this.sketches[posixPath] = sketch;
+  }
+
+  getSketch(path: string): Create.Sketch | null {
+    return this.sketches[path] || null;
+  }
+}