Ordering By Relation Aggregates with Where Clauses

Problem

Currently Relation Aggregates only support _count with asc and desc. One would hope that it would support relation aggregates with where subqueries.

Suggested solution

The ability to add subqueries with where clauses inside _count.

Example:

orderBy: {
  table2: {
    table2_key: {
      _count: 'desc',
      where: {
        foo: 'bar'
      }
    }
  }
}

Alternatives

Right now you need to write a raw query, example:

SELECT 
  key1,
  key2,
  (SELECT COUNT(*) FROM table2 WHERE table2.key1 = 'bar') AS sortingKey
FROM table1
JOIN table2 ON table1.table2_id = table2.id
ORDER BY sortingKey DESC

No source file, test, or entry point is named in the issue. Start by locating Prisma's relation-aggregate orderBy implementation and its tests, then define coverage for filtered _count aggregates and verify that the requested nested where syntax produces the expected ordering.