Improve python object constructors rendering

[tamarinvs19]

Description

Replaced copyreg._reconstructor by constructor from fuzzer or __new__ method from serializer.

Updated strategy for state before / state after comparison: assertions will generate only if argument have been changed inside a tested function.

Additional changes:

• group kind and module
• add field for kwargs
• improve rendering
• add comparator for recursive objects

Fixes #2077

How to test

Manual tests

1. Try to generate tests for a function or method with user object, e.g.

class Node:
    def __init__(self, name: str, children: List[Node]):
        self.name = name
        self.children = children

    def __eq__(self, other):
        if isinstance(other, Node):
            return self.name == other.name
        else:
            return False

    def add_child(self, child: Node):
        self.children.append(child)

Expected constructors: no one copyreg._reconstructor, tests are similar to

class TestNode(unittest.TestCase):
    # region Test suites for executable samples.graph.add_child
    
    # region FUZZER
    
    def test_add_child(self):
        """
        self = samples.graph.Node
        child = samples.graph.Node
        """
        node = samples.graph.Node("foo", [])
        child = samples.graph.Node("abcdefghijklmnopqrst", [])
        child1 = child
        
        actual = node.add_child(child1)
        
        self.assertEqual(None, actual)
        
        child_modified = object.__new__(samples.graph.Node)
        list1 = object.__new__(samples.graph.Node)
        list1.name = 'foo'
        list1.children = [child_modified]
        child_modified.name = 'abcdefghijklmnopqrst'
        child_modified.children = [list1]
        
        self.assertEqual(child_modified, child1)
        
        self.assertEqual(list1, node)
    # endregion
    
    # endregion

Self-check list

Check off the item if the statement is true. Hint: [x] is a marked item.

Please do not delete the list or its items.

• 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.