Extract Function: Fix NPE when extracting this in object
 #KT-6238 Fixed
Change Signature: Do not add default values to parameters of overriding functions
 #KT-6160 Fixed
Change Signature: Update enum entries w/o delegation specifier when changing signature of enum class constructor
 #KT-5978 Fixed
Change Signature: Rename parameter in overriding functions
 #KT-4045 Fixed
Change Signature: Add support of multi-file tests
Change Signature: Processing of non-Kotlin usages
 #KT-5810 Fixed
 #KT-4187 Fixed
Light Methods: Change PSI element language to Kotlin
Change Signature: Allow running Java's Change Signature in tests
Change Signature: Allow running Kotlin change signature from Java usage/override
Change Signature: Allow running Java change signature from Kotlin usage/override
Change Signature: Process Kotlin-based usages when changing signature of the Java function
Fixed case of file name.
Moved test data into common directory.