support for redshift super -> feast array types.

[robhowley]

Is your feature request related to a problem? Please describe.
Redshift's super column type allows for JSON. Currently the best approach with feast appears to be using either ValueType.Bytes with a super column or ValueType.String with a varchar and serialize the data ahead of time. Neither are optimal since the online store will then receive either bytes or a string instead of an array.

Describe the solution you'd like
Would like to be able to define a column as Array(base_type=[appropriate primitive) for Field backed by a super column. When we materialize the appropriate type is loaded into and eventually returned from the online stoer at request time.

Describe alternatives you've considered
Working with json strings or bytes and having the client be in charge of deserializing.

Thanks