[mlir][sparse] Improve the implementation of sparse_tensor.new for the codegen path.

Rewrite a NewOp into a NewOp of a sorted COO tensor and a ConvertOp for
converting the sorted COO tensor to the destination tensor type.

Codegen a NewOp of a sorted COO tensor to use the new bulk reader API and sort
the elements only when the input is not sorted.

Reviewed By: aartbik

Differential Revision: https://reviews.llvm.org/D144504