Forwarding version of TryInto and TryFrom

[JelteF]

We can currently forward From, but not TryFrom. Implementing this for a single field would be fairly easy. For multiple fields this would be harder/impossible, because we would have to figure out what to do with the multiple possibly different errors that you can get. This would probably mean creating a temporary enum.

For TryInto we only support deriving it for an enum, but we don't allow forwarding it to the inner field. This should also be supported. For a struct with multiple fields this would have the same problem as TryFrom.