Use deep equality for mock results

[Damtev]

Description

If a returned value in the method under test is mocked, we cannot use assertEquals because the equals method for mocks works differently. So, we need to use deep equality in such cases.

Fixes #1877.

How to test

Automated tests

Common pipeline.

Manual tests

The same as in the corresponding issue.

Generated test:

///region SYMBOLIC EXECUTION: SUCCESSFUL EXECUTIONS for method provideObject()

/**
 * @utbot.classUnderTest {@link ProviderImpl}
 * @utbot.methodUnderTest {@link ProviderImpl#provideObject()}
 * @utbot.returnsFrom {@code return new ExampleClass(0);}
 */
@Test
@DisplayName("provideObject: -> return new ExampleClass(0)")
public void testProvideObject_Return() {
    org.mockito.MockedConstruction mockedConstruction = null;
    try {
        java.util.concurrent.atomic.AtomicInteger mockClassCounter = new java.util.concurrent.atomic.AtomicInteger();
        mockedConstruction = mockConstruction(ExampleClass.class, (ExampleClass ExampleClassMock, org.mockito.MockedConstruction.Context context) -> {
            switch (mockClassCounter.get()) {
                case 0:
                    break;
            }
            mockClassCounter.getAndIncrement();
        });
        ProviderImpl providerImpl = new ProviderImpl();

        ExampleClass actual = providerImpl.provideObject();

        ExampleClass expectedMock = mock(ExampleClass.class);
        expectedMock.field = 0;
        int expectedMockField = expectedMock.field;
        int actualField = actual.field;
        assertEquals(expectedMockField, actualField);

    } finally {
        mockedConstruction.close();
    }
}
///endregion

As can be seen, deep equality is used here.

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.