To check that boolean "is" prefix is treated correctly, and Unit return
type is not translated to void. `@Deprecated` annotations are added just
so that the `$annotations` methods would also be generated.
Also adds rendering of @Metadata annotations in Kapt3 and Kapt4 tests
(currently disabled for a few tests).
Co-authored-by: Alexander Udalov <alexander.udalov@jetbrains.com>