Problem

Several functional gaps and shortcommings were identified during integrating VerificationEngine into sdk integration tests
#3868

Solution

Added:

• optional explicit include list for verification (for cases where we need to verify just few or single file(s))
• ability to prepend testing method name to verification subdir
• ability to more colsely influence verification subditr name (custom distinguisher, template parameters in name are switchable)
• delete templating outputs if they are in temp location

Checks:

• Added unit tests
• Added #nullable enable to all the modified files ?