Fix where query criteria with multiple associations joins

[igdianov]

query {
  Tasks(
    where: {
      status: { EQ: COMPLETED }
      AND: [
        { variables: { name: { EQ: "variable1" }, value: { EQ: "data" } } }
        { variables: { name: { EQ: "variable2" }, value: { EQ: true } } }
      ]
    }
  ) {
    select {
      id
      status
      variables {
        name
        value
      }
    }
  }
}