SQL STRING_AGG function in groupBy

new Query().from({ brand: brandsCollection })
      .innerJoin({ productBrand: productBrandsCollection }, ({ productBrand, brand }) => eq(productBrand.brandId, brand.id))
      .groupBy(({ productBrand }) => productBrand.productId)
      .select(({ brand, productBrand }) => ({
        id: productBrand.productId,
        brands: stringAgg(brand.name, ", ", { orderBy: { val: productBrand.order, order: "asc" | "desc" }}),
      }))

result

[
  { id: 1, brands: "coca, fanta" },
]

Start at the Query.groupBy entry point and the stringAgg usage shown in the issue, then trace how grouped selections are translated. Implement the requested ordered STRING_AGG behavior and verify that the example produces one row with the comma-separated brand names.