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/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,
         })