[Improvement] Dialog: add before-close prop (#881)

types/dialog.d.ts

@@ -3,6 +3,7 @@ export type DialogOptions = {
   message?: string;
   overlay?: boolean;
   lockScroll?: boolean;
+  beforeClose?: (action: string, done: function) => void;
   confirmButtonText?: string;
   cancelButtonText?: string;
   showConfirmButton?: boolean;