Fix isos and lenses generation in case of parameters having keywords as names.

[lukasz-kusek]

Data classes which use parameters that have names which are Kotlin keywords and need to be escaped fail to compile:

data class LensData<T>(
    val `in`: T
) { companion object }

This change makes generation of isos an lenses work with such parameters.

There's an additional test added that requires some additional fix in the code which is outside of the scope of this change.