fix [3118445] Transform * Transform does not work as expected

The problem wasn't in the multiply operator, but rather in the code
that built the transform from the HAL bitmask.

We now use the multiply operator to build the Transform from the bitmask,
which guarantees, it'll always be correct.

Also added a simple test for Transform.

Change-Id: I09bf3b0e51d92f59d83ea91c4cc94fc2aa0bf227