Loop Transformation: Add support for do-while loops

The current loop transformation for `scf.while` only supports while loops, where the "before" region only contains operations related to generating a condition, which is used as an operand in the `scf.condition` operation. However, this transformation does not support do-while loops, where the "before" region can include more operations that updates argument(s) that maybe used in the "after" region. The transformation is part of this data-oblivious transformation pipeline #777.