[MLv2] [FE] Remove aggregate, breakout, filter methods from Question

[ranquild]

There should be no Question-level functions like this. Migrate places that use them to use the legacy StructuredQuery and remove these functions from the Question class.

Before:

const newQuestion = question.aggregate(["count"]);

After:

const newQuestion = question
  .legacyQuery({ useStructuredQuery: true })
  .aggregate(["count"])
  .question();
;