Support for union type

[bobsingor]

I would like to use auto relay for union types:
https://typegraphql.com/docs/1.1.1/unions.html

Trying to use it with union types will give me the following typescript error:
Type 'Document | Folder' is not assignable to type 'ClassType<any>'.

It's not just a typescript error because if I try to do
@RelayedQuery(() => SearchResultUnion as any)

I will get undefinedConnection as a return type inside my graphql schema