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'));
```

new-docs/puppeteer.jshandle.evaluatehandle.md

@@ -9,19 +9,19 @@ This method passes this handle as the first argument to `pageFunction`<!-- -->.
 <b>Signature:</b>
 
 ```typescript
-evaluateHandle(pageFunction: Function | string, ...args: unknown[]): Promise<JSHandle>;
+evaluateHandle<HandleType extends JSHandle | ElementHandle = JSHandle>(pageFunction: EvaluateHandleFn, ...args: SerializableOrJSHandle[]): Promise<HandleType>;
 ```
 
 ## Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
-|  pageFunction | Function \| string |  |
-|  args | unknown\[\] |  |
+|  pageFunction | [EvaluateHandleFn](./puppeteer.evaluatehandlefn.md) |  |
+|  args | [SerializableOrJSHandle](./puppeteer.serializableorjshandle.md)<!-- -->\[\] |  |
 
 <b>Returns:</b>
 
-Promise&lt;[JSHandle](./puppeteer.jshandle.md)<!-- -->&gt;
+Promise&lt;HandleType&gt;
 
 ## Remarks