Write `Display` and `Debug` traits for uniffi Records and Enums

[thunderbiscuit]

This is now available as of uniffi-rs 0.30.0.

Note that it doesn't work on pure enums, and only on enums that hold data (the ones that get transformed into sealed classes in Kotlin).

Notes:

• Both Debug and Display will generate the toString() method in Kotlin, with the Display taking precedence over Debug if it exists.
• The Debug will generate the __repr__ and the Display will generate __str__ methods in Python.
• Swift? I need to test.