Add size property to ReadonlySearchParams (#53144)

Closes #49774 (and my dupe #53141), where there's a type error when attempting to construct URLSearchParams from ReadonlyURLSearchParams, [as recommended in the Next docs here](https://nextjs.org/docs/app/api-reference/functions/use-search-params#updating-searchparams) and breaks `next build` on Node v18.16.0+, including on Vercel.


This is blocked by TS publishing the new `dom` types (microsoft/TypeScript#54466). The [URL Standard](https://url.spec.whatwg.org/#dom-urlsearchparams-size) added the size property to URLSearchParams (whatwg/url#734) and this now has wide [browser support](https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams/size).

packages/next/src/client/components/navigation.test.ts

@@ -0,0 +1,9 @@
+import { ReadonlyURLSearchParams } from './navigation'
+
+describe('next/navigation', () => {
+  it('should be able to construct URLSearchParams from ReadonlyURLSearchParams', () => {
+    const searchParams = new URLSearchParams('?foo=test&bar=test')
+    const readonlySearchParams = new ReadonlyURLSearchParams(searchParams)
+    expect(() => new URLSearchParams(readonlySearchParams)).not.toThrow()
+  })
+})

packages/next/src/client/components/navigation.ts

@@ -33,6 +33,7 @@ export class ReadonlyURLSearchParams {
   keys: URLSearchParams['keys']
   values: URLSearchParams['values']
   toString: URLSearchParams['toString']
+  size: any | URLSearchParams['size']
 
   constructor(urlSearchParams: URLSearchParams) {
     this[INTERNAL_URLSEARCHPARAMS_INSTANCE] = urlSearchParams
@@ -45,6 +46,7 @@ export class ReadonlyURLSearchParams {
     this.keys = urlSearchParams.keys.bind(urlSearchParams)
     this.values = urlSearchParams.values.bind(urlSearchParams)
     this.toString = urlSearchParams.toString.bind(urlSearchParams)
+    this.size = urlSearchParams.size
   }
   [Symbol.iterator]() {
     return this[INTERNAL_URLSEARCHPARAMS_INSTANCE][Symbol.iterator]()