Join the functionality of ValueConstructor and MockValueConstructor

[EgorkaKulikov]

Description

There are two classes in UnitTestBot with the same responsibility ValueConstructor and MockValueConstructor.

Both of them are responsible for converting UtModel to UtConcreteValue and located in instrumented process. Mostly MockValueConstructor is used because it is a wrapper of ValueConstructor with additional logic for mocks. However, ValueConstructor is also used. This is very unclear and requires supporting similar copypasted codebase.

The refactoring joining ValueConstructor and MockValueConstructor is required.