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.page.waitfor.md

@@ -12,7 +12,7 @@ waitFor(selectorOrFunctionOrTimeout: string | number | Function, options?: {
         hidden?: boolean;
         timeout?: number;
         polling?: string | number;
-    }, ...args: unknown[]): Promise<JSHandle>;
+    }, ...args: SerializableOrJSHandle[]): Promise<JSHandle>;
 ```
 
 ## Parameters
@@ -21,7 +21,7 @@ waitFor(selectorOrFunctionOrTimeout: string | number | Function, options?: {
 |  --- | --- | --- |
 |  selectorOrFunctionOrTimeout | string \| number \| Function |  |
 |  options | { visible?: boolean; hidden?: boolean; timeout?: number; polling?: string \| number; } |  |
-|  args | unknown\[\] |  |
+|  args | [SerializableOrJSHandle](./puppeteer.serializableorjshandle.md)<!-- -->\[\] |  |
 
 <b>Returns:</b>