[Task] InputBlockV2 - Usage in ranking models high-level API

[gabrielspmoreira]

Change the following higher-level API ranking models to use the new InputBlockV2.
This is part of RMP #479, which you can check for more context

• DCNModel
• DeepFMModel

[viswa-nvidia]

@gabrielspmoreira , please follow the template and add the problem statement, goal, constraints and starting point.