Refactor CgSpringVariableConstructor

[EgorkaKulikov]

Description

Current design of CgSpringVariableConstructor is bad.

The following action is repeated three times for different annotations:

• we try to find a variable
• if variable is already created, use some custom fields construction

We can possibly implement some kind of Map<Annotation, ProcessingDelegate> and iterate by it.

[IlyaMuravjov]

I think, it's better to have some sort of List<CgFieldManager> where CgFieldManager is:

interface CgFieldManager {
    fun collectFields(testSets: List<CgMethodTestSet>): List<CgField>

    fun overrideValueCreationIfNeeded(model: UtModel): CgValue?
}

Here CgFieldCreator can encapsulate logic related to use of some kind of fields. For example, CgAutowiredFieldManager can encapsulate logic needed for recognition of bean models, creating and annotating corresponding fields, and construction of values for such models.