Refactor FastFilterRewriteHelper

[bowenlan-amzn]

As we apply the optimization to more aggregator like #13531 and upcoming #14189. The helper class now becomes huge.

Also the logics of performing the optimization requires refactoring, more details from these comments
#13865 (comment)
#13865 (comment)
#13865 (comment)
#13865 (comment)
#13865 (comment)

AggregationType is to provide Helper access to some fields of aggregator.
Now the Rewriteable check and init AggregationType is a bit intertwined, better to refactor to segregate them.
The logic flow in aggregator would be

• init context object with rewriteable flag as false
• check if rewriteable
• build ranges with aggregator providing any needed fields

Can also see if we are able to refactor the term aggregation optimization easily into one path