Equality operator for rfl::Generic and rfl::Object

Hello, we sometimes embed Generic inside of types like:

```cpp
struct Foo {
  std::string x;
  rfl::Generic extras;
};
```

But then, in order to default `operator==` for `Foo`, we need to define our own `operator==` for `rfl::Generic`. The same thing applies to `rfl::Object`. Would it be possible to provide that as part of the library? If this sounds ok I'm happy to submit a PR.

Thanks.