Create a AggregationConfig class for each AggregationType

[ThomsonTan]

Follow up for the following comment. The View constructor accepts both AggregationType and AggregationConfig because the base AggregationConfig stores config for multiple AggregationTypes. Create a AggregationConfig for each AggregationType could simplify the View constructor signature. The cons is it will the SDK API.

#3732 (comment)

[marcalff]

Now that #3732 has been merged, this change is no longer necessary.

Closing.