feat(types): add (and fix) evaluateHandle types (#6130)

This change started as a small change to pull types from DefinitelyTyped over to
Puppeteer for the `evaluateHandle` function but instead ended up also fixing
what looks to be a long standing issue with our existing documentation.

`evaluateHandle` can in fact return an `ElementHandle` rather than a `JSHandle`.
Note that `ElementHandle` extends `JSHandle` so whilst the docs are technically
correct (all ElementHandles are JSHandles) it's confusing because JSHandles
don't have methods like `click` on them, but ElementHandles do.

if you return something that is an HTML element:

```
const button = page.evaluateHandle(() => document.querySelector('button'));
// this is an ElementHandle, not a JSHandle
```

Therefore I've updated the original docs and added a large explanation to the
TSDoc for `page.evaluateHandle`.

In TypeScript land we'll assume the function will return a `JSHandle` but you
can tell TS otherwise via the generic argument, which can only be `JSHandle`
(the default) or `ElementHandle`:

```
const button = page.evaluateHandle<ElementHandle>(() => document.querySelector('button'));
```

test/elementhandle.spec.ts

@@ -182,17 +182,11 @@ describe('ElementHandle specs', function () {
       const { page, server } = getTestState();
 
       await page.goto(server.PREFIX + '/shadow.html');
-      const buttonHandle = await page.evaluateHandle(
+      const buttonHandle = await page.evaluateHandle<ElementHandle>(
         // @ts-expect-error button is expected to be in the page's scope.
         () => button
       );
-      // TODO (@jackfranklin): TS types are off here. evaluateHandle returns a
-      // JSHandle but that doesn't have a click() method. In this case it seems
-      // to return an ElementHandle. I'm not sure if the tests are wrong here
-      // and should use evaluate<ElementHandle> or if the type of evaluateHandle
-      // should change to enable the user to tell us they are expecting an
-      // ElementHandle rather than the default JSHandle.
-      await (buttonHandle as ElementHandle).click();
+      await buttonHandle.click();
       expect(
         await page.evaluate(
           // @ts-expect-error clicked is expected to be in the page's scope.

test/jshandle.spec.ts

@@ -53,6 +53,7 @@ describe('JSHandle', function () {
       const aHandle = await page.evaluateHandle(() => document.body);
       let error = null;
       await page
+        // @ts-expect-error we are deliberately passing a bad type here (nested object)
         .evaluateHandle((opts) => opts.elem.querySelector('p'), {
           elem: aHandle,
         })