refactor(qc): remove aggregation object logic (#5608)
[ORM-1008](https://linear.app/prisma-company/issue/ORM-1008/remove-aggregation-aliasing-logic)
Removes the intermediate object used by aggregations and adjusts the
data mapper and aggregation query builder code to parse the query
results directly. Also centralizes the logic for aliases of aggregated
columns in `aggregate_selection.rs`.
Prisma PR: https://github.com/prisma/prisma/pull/27995
/prisma-branch refactor/remove-aggregation-object-logic
