docs: add next js with app router example (#7552)

* move the existing example to with-script-in-browser

* Add example with next js app router

* disable ssr for excalidraw client comp

* typo

* update output dir

* don't include nextjs example in tsconfig

* remove meta.json

* lint

* remove example.ts

* port

* move the examples outside packages and use the deps as workspaces in examples

* update gitignore

* fix example

* update path of build dir

* fix

* fix scripts

* try local path

* fix

* update commands

* fix

* fix

* fix script

* skip ts

* disable ts

* add vercel.json

* install

* update tsconfig

* fix lint

* remove console.log

* lets see if this works

* revert

* remove ts nocheck

* add types and some utils in nextjs example

* fix types

* updatw example and remove nextjs dynamic syntax so we don't import excal twice

* move both examples to workspaces and create generic example to be used by browser and next js both

* copy the static assets to nextjs

* fix ts config

* render custom menu items

* fix custom footer

* fix types in browser example

* use regular imports for importing excal and import it using dynamic next js in app router instead

* Add example for pages router

* fix css discrepancies

* fix css

* configure output dir

* fix

* fix css

* rename to with-nextjs

* move components to examples/excalidraw/components

examples/excalidraw/with-nextjs/src/pages/excalidraw-in-pages.tsx

@@ -0,0 +1,22 @@
+import dynamic from "next/dynamic";
+import "../common.scss";
+
+// Since client components get prerenderd on server as well hence importing the excalidraw stuff dynamically
+// with ssr false
+const Excalidraw = dynamic(
+  async () => (await import("../excalidrawWrapper")).default,
+  {
+    ssr: false,
+  },
+);
+
+export default function Page() {
+  return (
+    <>
+      <a href="/">Switch to App router</a>
+      <h1 className="page-title">Pages Router</h1>
+      {/* @ts-expect-error - https://github.com/vercel/next.js/issues/42292 */}
+      <Excalidraw />
+    </>
+  );
+}