fix(cloud): async iterators

Author: Cubelrti

types/wx/lib.wx.cloud.d.ts

@@ -20,6 +20,8 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 ***************************************************************************** */
 
+/// <reference lib="es2018.asynciterable" />
+
 /**
  * Common interfaces and types
  */
@@ -285,10 +287,12 @@ declare namespace ICloud {
         data: string
         json?: any
     }
+    
     interface AsyncIterator<T> {
         next(value?: any): Promise<IteratorResult<T>>;
         return?(value?: any): Promise<IteratorResult<T>>;
         throw?(e?: any): Promise<IteratorResult<T>>;
+        [Symbol.asyncIterator](): AsyncIterableIterator<T>;
     }
     interface ICloudAIStreamResult {
         textStream: AsyncIterator<string>