feat(v2): Support swizzling TypeScript components (#2671)

* feat(v2): Support swizzling TypeScript components

* Add tsc --noEmit to tsc script in theme-classic

Now everything can pass the type checker! (although still a lot of any)

* Add tsconfig and types.d.ts to website

Improve developer experience.

As an example, I converted NotFound to tsx

* Apply type annotation suggestions

* Do not fallback to `getThemePath` if getTypeScriptThemePath is undefined

* Fix tsc

* Add module declaration for @theme-original/*

* Move babel cli to root package.json

packages/docusaurus-theme-classic/src/theme/hooks/useScrollPosition.ts

@@ -0,0 +1,47 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {useState, useEffect} from 'react';
+import ExecutionEnvironment from '@docusaurus/ExecutionEnvironment';
+
+type ScrollPosition = {scrollX: number; scrollY: number};
+
+const getScrollPosition = (): ScrollPosition => ({
+  scrollX: ExecutionEnvironment.canUseDOM ? window.pageXOffset : 0,
+  scrollY: ExecutionEnvironment.canUseDOM ? window.pageYOffset : 0,
+});
+
+const useScrollPosition = (
+  effect: (position: ScrollPosition) => void,
+  deps = [],
+): ScrollPosition => {
+  const [scrollPosition, setScrollPosition] = useState(getScrollPosition());
+
+  const handleScroll = () => {
+    const currentScrollPosition = getScrollPosition();
+
+    setScrollPosition(currentScrollPosition);
+
+    if (effect) {
+      effect(currentScrollPosition);
+    }
+  };
+
+  useEffect(() => {
+    window.addEventListener('scroll', handleScroll);
+
+    return () =>
+      window.removeEventListener('scroll', handleScroll, {
+        // @ts-expect-error: See https://github.com/microsoft/TypeScript/issues/32912
+        passive: true,
+      });
+  }, deps);
+
+  return scrollPosition;
+};
+
+export default useScrollPosition;