DataFlowValueFactory and its environment refactoring: containing declaration is added into factory functions
as an argument and used to determine identifier stability. A few minor fixes. #KT-5907 Fixed. #KT-4450 Fixed. #KT-4409 Fixed.
New tests for KT-4409, KT-4450, KT-5907 (public and protected value properties used from the same module or not,
open properties, variable properties, delegated properties, properties with non-default getter).
Public val test and KT-362 test changed accordingly.
And String.length as well.
This is done for JVM interoperability: java.lang.CharSequence is an open class
and has a function 'length()' which should be implemented in subclasses
somehow.
A minor unexpected effect of this is that String.length() is now a compile-time
constant (it wasn't such as a property because properties are not supported in
compile-time constant evaluation)
#KT-3571 Fixed