We are going to deprecate `WITH_RUNTIME` directive. The main reason
behind this change is that `WITH_STDLIB` directive better describes
its meaning, specifically it will add kotlin stdlib to test's classpath.
Simplify MultifileClassPartCodegen, remove related tests and change some
tests to use const val instead of val because backing fields for const
properties are stored in the facade, not parts
#KT-23701 Fixed
Ivan Kylchik