next-apollo not forwarding static properties on components it wraps

If I'm not wrong, it's currently not possible to work with [nested layouts](https://adamwathan.me/2019/10/17/persistent-layout-patterns-in-nextjs/) in next-apollo because it doesn't forward the `Layout` property in an example like

```ts
const GroupMembersPage = GroupMembers;

GroupMembersPage.Layout = GroupLayout;

export default withApollo({ ssr: true })(GroupMembersPage);
```

to the `_app` page which is quite limiting. If this is something you are interested in supporting (and I don't see why not) I'm happy to open a PR for it