[new feature] ImagePreview: add className prop (#2433)

types/dialog.d.ts

@@ -5,7 +5,7 @@ export type DialogOptions = {
   title?: string;
   message?: string;
   overlay?: boolean;
-  className?: string;
+  className?: any;
   lockScroll?: boolean;
   messageAlign?: string;
   confirmButtonText?: string;

types/image-preview.d.ts

@@ -1,9 +1,12 @@
 import { VanPopupMixin } from './mixins/popup';
 
 export type ImagePreviewOptions = string[] | {
+  loop?: boolean;
   images: string[];
+  className?: any;
   startPosition?: number;
   showIndex?: boolean;
+  asyncClose?: boolean;
   showIndicators?: boolean;
   onClose?: () => any;
 };