Introduce casting yaml Pipeline's config to a Config class

[AlekseySh]

The current approach:
yaml -> (calling hydra) -> dictionary
The proposed one:
yaml -> (calling hydra) -> dictionary -> Config
or
yaml -> -> Config

Motivation:

• Have all the customizable fields in one place that you can print or work with (there is no way to do so for yaml because of missed fields fill up by registry silently)
• We can check there are no extra fields in the config (and other checks)
• Another (probably more flexible way) to setup Pipelines