Add Data instance to Record

[locallycompact]

I think this is right

[Dridus]

@asariley @dfithian can one of you shepherd this PR? I assigned you both to review, but what I really mean is either one of you

[dfithian]

This seems reasonable, but I wonder if it should really be defined in the Vinyl library, since there's nothing specific to Composite about the code that was added. If you were to do that, we might need to do some more work to get it compiling with Vinyl 0.14, since that's not allowed by our version constraints.

In that case, you might just keep using your fork in the short term and we can work on supporting Vinyl 0.14.

[dfithian]

The latest ghc 9.2.2 branch supports vinyl 0.14, so if that was added it would get pulled in automatically. I think we could probably close this now?

[locallycompact]

I think we will still need this bit

deriving instance (Typeable k, Data k, KnownSymbol s) => Data (s :-> k)

Let me just check I can correctly implement the rest for Rec f because at the minute it is Rec Data.Functor.Identity