Implement working Clone and PartialEq on DataPayload and Yoke

[sffc]

Currently, the Clone impl is present for Yoke and DataPayload, but it does not work when one tries to use it. The error looks like this:

note: the following trait bounds were not satisfied:
      `<hello_world::HelloWorldV1<'static> as Yokeable<'a>>::Output: Clone`

This seems to be caused by rust-lang/rust#85636. However, the workaround mentioned there does not work for Clone, since the Clone impl for a reference copies the reference instead of cloning the struct that the reference points to.

PartialEq is a related but separate issue. I have the following impl, but it doesn't compile:

impl<'d, 's, M> PartialEq for DataPayload<'d, 's, M>
where
    M: DataMarker<'s>,
    for<'a> &'a <M::Yokeable as Yokeable<'a>>::Output: PartialEq,
{
    fn eq(&self, other: &Self) -> bool {
        self.get().eq(other)
    }
}

Error message:

error[E0308]: mismatched types
   --> provider/core/src/data_provider.rs:165:23
    |
165 |         self.get().eq(other)
    |                       ^^^^^ expected reference, found struct `data_provider::DataPayload`
    |
    = note: expected reference `&&<<M as marker::DataMarker<'s>>::Yokeable as Yokeable<'_>>::Output`
               found reference `&data_provider::DataPayload<'d, 's, M>`

I played around with different variations of & and * on the arguments to get them to match up, to no success. My guess is that the compiler is just confused about the lifetimes, since the lifetime of .get() is different than the lifetime of other.

CC @Manishearth

[Manishearth]

I think we fixed this with yoke_trait_hack, yes? Can this issue be closed?

[sffc]

It's implemented for Yoke, but we still need to it for DataPayload I think