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/useTabGroupChoice.ts

@@ -0,0 +1,52 @@
+/**
+ * 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, useCallback, useEffect} from 'react';
+
+const TAB_CHOICE_PREFIX = 'docusaurus.tab.';
+
+const useTabGroupChoice = (): {
+  tabGroupChoices: {readonly [groupId: string]: string};
+  setTabGroupChoices: (groupId: string, newChoice: string) => void;
+} => {
+  const [tabGroupChoices, setChoices] = useState<{
+    readonly [groupId: string]: string;
+  }>({});
+  const setChoiceSyncWithLocalStorage = useCallback((groupId, newChoice) => {
+    try {
+      localStorage.setItem(`${TAB_CHOICE_PREFIX}${groupId}`, newChoice);
+    } catch (err) {
+      console.error(err);
+    }
+  }, []);
+
+  useEffect(() => {
+    try {
+      const localStorageChoices = {};
+      for (let i = 0; i < localStorage.length; i += 1) {
+        const storageKey = localStorage.key(i) as string;
+        if (storageKey.startsWith(TAB_CHOICE_PREFIX)) {
+          const groupId = storageKey.substring(TAB_CHOICE_PREFIX.length);
+          localStorageChoices[groupId] = localStorage.getItem(storageKey);
+        }
+      }
+      setChoices(localStorageChoices);
+    } catch (err) {
+      console.error(err);
+    }
+  }, []);
+
+  return {
+    tabGroupChoices,
+    setTabGroupChoices: (groupId: string, newChoice: string) => {
+      setChoices((oldChoices) => ({...oldChoices, [groupId]: newChoice}));
+      setChoiceSyncWithLocalStorage(groupId, newChoice);
+    },
+  };
+};
+
+export default useTabGroupChoice;