Description

Spring unit tests require to inject Mockito mocks in different way than pure Java tests.
To do it, we require per-class variables for all instances whose methods will be mocked in tests.
To collect per-class variables, we traverse all UtModels in test sets to find mocked classes.

Some refactoring of Cg-instances introduced: we would like to minimize regressions in standard codegen process.

How to test

Should not be tested separately, just some preparation logic for future Spring codegen and rendering.
Logic is temporarly disabled in main: isSpringClass=false.

Self-check list

• I've set the proper labels for my PR (at least, for category and component).
• PR title and description are clear and intelligible.
• I've added enough comments to my code, particularly in hard-to-understand areas.
• The functionality I've repaired, changed or added is covered with automated tests.
• Manual tests have been provided optionally.
• The documentation for the functionality I've been working on is up-to-date.