DSSM default model fix

[blondered]

Feature Description

Right now DSSMModel has one parameter without the default value: dataset_type: TorchDataset[tp.Any]. This is very confusing since DSSMModel also has a default model. But user can't use it out of the box.

Why this feature?

DSSMModel doesn't follow the simple interface from other RecTools models

Additional context

No response