Data source conversion from protobuf doesn't use type information


For some reason we are using field names https://github.com/feast-dev/feast/blob/b35e1e84720523cef70cba6d6306af8f193b469f/sdk/python/feast/data_source.py#L217 to infer data source types. We should be using the actual data source types in the protos.


Also, https://github.com/feast-dev/feast/blob/b35e1e84720523cef70cba6d6306af8f193b469f/sdk/python/feast/data_source.py#L213 doesnt exist