Ensure latest react-dom types for experimental release channel are us…

…ed (#49049)

Same as #48641 but for `react-dom`.

Required to get types new form hooks, Float etc.

packages/next/types/index.d.ts

@@ -2,6 +2,7 @@
 /// <reference types="react" />
 /// <reference types="react/experimental" />
 /// <reference types="react-dom" />
+/// <reference types="react-dom/experimental" />
 
 import React from 'react'
 import { ParsedUrlQuery } from 'querystring'