feat: add clear all workspaces

packages/data-center/src/datacenter.ts

@@ -279,6 +279,16 @@ export class DataCenter {
     return await this._transWorkspaceProvider(workspace, 'affine');
   }
 
+  /**
+   * @deprecated
+   * clear all workspaces and data
+   */
+  public async clear() {
+    for (const provider of this.providerMap.values()) {
+      await provider.clear();
+    }
+  }
+
   /**
    * Select a file to import the workspace
    * @param {File} file file of workspace.