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

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.

Start by checking the uniffi-rs 0.30.0 behavior described in the issue for Records and data-holding Enums. Verify generated Kotlin toString(), Python __repr__ and __str__, and Swift output; done would require confirming the expected trait precedence and determining whether pure enums remain unsupported.

Written by the indexing model from the issue text.