Add torch.Tensor as option for online and offline retrieval

[franciscojavierarceo]

Is your feature request related to a problem? Please describe.
Feast should create an extra to support PyTorch tensors as a first-class citizen.

Describe the solution you'd like

# Fetch features from Feast
 feature_vector = feature_store.get_online_features(
        entity_rows=[entity_row],       
       features=self.feature_refs
 ).to_tensor(kind='torch') # default is torch, could support Tensorflow later

Describe alternatives you've considered
N/A

Additional context
N/A