Include asset type in asset object

**Is your feature request related to a problem? Please describe.**

Currently, the list assets and the get asset endpoints/method return object(s) that don't contain the asset type. We need to know the type of asset we are working it so we can filter away assets like penny stocks and ETF's.

**Describe the solution you'd like**

We need to know if the asset is a common stock, penny stock, ETF e.t.c We checked polygon's documentation and we observed that the asset type is attached to the asset object.