UI Test Cleanup: Split up checked_unwrap tests
Let's slowly bring that ticket closer to the finish line 🐌🏁
This splits up `tests/ui/checked_unwrap.rs` into:
* `tests/ui/checked_unwrap/complex.rs`
* `tests/ui/checked_unwrap/simple.rs`
Based on the naming of the methods in the tests.
changelog: none
cc #2038