Add possibility to compare expected response with actual one in Contacts Integration Tests

[dr-3lo]

In Contacts integration tests it is good idea to implement custom comparer for Contact, it will allow to check what actual response result we got from our models for test request.

ex.
```

    //load request from file
    using var responseContent = await Feature.LoadFileToStringContent();

    //new logic: get response object from string
    var responseStream = await responseContent.ReadAsStreamAsync();
    var expectedResponse = await JsonSerializer.DeserializeAsync<CreateContactResponse>(responseStream, _jsonSerializerOptions);
    responseStream.Position = 0; // Reset stream position for mock response

    ...

    // Act
    ...

    // Assert
    mockHttp.VerifyNoOutstandingExpectation();
    result.Should().NotBeNull();

    //new logic: use expectedResponse to verify result 
    result.Should().BeEquivalentTo(expectedResponse);

    }